Catalyst for esterification and transesterification and process for producing ester

ABSTRACT

This invention relates to an activated titanium catalyst used in an esterification reaction and/or a transesterification reaction, and a method of manufacturing esters having a low acid value and narrow molecular weight distribution by making effective use of the excellent dehydration esterification reaction properties and transesterification ability of this catalyst. Specifically, this invention is a catalyst for an esterification reaction and/or a transesterification reaction, which is a gel-like substance comprising a mixture of an alkoxytitanium, water-soluble polyol and water, or the reaction product thereof, wherein the number of moles of said water-soluble polyol and said water relative to 1 mole of titanium, is respectively 1-50 moles and 1-60 moles. For example, an objective polyester can be produced in a method of producing an ester comprising, a first step wherein a diol is reacted with an ester produced beforehand from a dibasic acid and a monofunctional alcohol, or an ester produced beforehand from a monofunctional alcohol and diol, a second step wherein unreacted ester is separated from the product produced in the first step to obtain another ester, and a third step wherein unreacted ester separated in the second step is recycled to the first step, 0.05-5 millimoles of the catalyst relative to one mole of acid being used in said first step.

FIELD OF THE INVENTION

This invention relates to a catalyst for esterification reactions andtransesterification reactions, and to a method of manufacturing estersusing this catalyst. More specifically, this invention relates to amethod of manufacturing esters having a low acid value and narrowmolecular weight distribution making use of the ability of thedehydration esterification reactivity and esterification potential of anactive titanium catalyst.

BACKGROUND OF THE INVENTION

In the past, catalysts such as sulfuric acid or alkoxytitanium have beenused for esterification reactions and transesterification reactions.

However, it is difficult to lower the acid value of the end product ofthe acid catalyst, while the reactivity of the alkoxytitanium is slow.

To improve the reactivity therefore, and easily remove catalystresidues, attempts have been made to further improve this alkoxytitaniumcatalyst, such as the polyol polytitanate produced by the reaction of analkoxytitanium and a low molecular weight polyol (Japanese Patent No.1795216) or the polytitanic acid arising from reaction of alkoxytitaniumand water (Japanese Patent No. 1885399).

When this alkoxytitanium is reacted with a water-soluble polyfunctionalpolyol, a polyol polytitanate is generated, and if this is furtherreacted with water, polytitanic acid is generated. When the polyolpolytitanate or polytitanic acid are used as catalysts, thepolytitanate/polytitanic acid reacts with alcohol and water whichproduces OH groups on the surface and activates them. However, althoughthe OH groups on the surface are activated, they are consumed as thereaction proceeds, the active sites disappear, and the catalyst becomesinactive.

Dioctyl phthalate has been used as a plasticizer for polyvinyl chlorideand it has a very high performance, but in outdoor applications, itvolatilizes due to its vapour pressure. In this regard, polyesters orcomplex esters produced from a dibasic acid, diol and monofunctionalalcohol can be used as non-volatile plasticizers. They exhibit excellentproperties, and are expected to have the same plasticizer capabilitycorresponding to their viscosity.

If is attempted to manufacture this type of ester using a catalyst ofthe prior art, the acid value does not decrease if there is not muchalcohol present in the system. However, if the alcohol is increased inorder to accelerate esterification and reduce the acid value, thepolymerization degree does not increase. As the reaction is performedusing an amount close to the stoichiometric amount to increase thepolymerization degree and produce the polyester, the acid value does notdecrease and the specification is still one order of magnitude too higheven for electrical components which require a low electricalconductivity. Thus, a low acid value polyester was desired. On the otherhand, complex esters having a low polymerization degree and a specificmolecular weight, have a molecular weight distribution which decreasesexponentially as the number n decreases and have a large number of lowmolecular weight molecules. This leads to a mixture with a large amountof diester with no diol component, and its separation is very difficult.Due to the heat history during separation, it was extremely difficult toimprove the shortcoming that the acid value of the component which it isdesired to use in the cycle increases.

Thus, a polyester or complex ester which could be used as a plasticizerfor polyvinyl chloride could not be manufactured in an actual productionprocess, and the environmental problem that large amounts of plasticizercontinue to be released from polyvinyl chloride has still not beenresolved.

PROBLEMS TO BE SOLVED BY THE INVENTION

It is therefore an object of this invention to provide a catalyst whichcan be used in esterification reactions and transesterificationreactions. This catalyst overcomes the aforesaid disadvantages of priorart catalysts based on alkoxytitanium which are used for esterificationreactions and transesterification reactions, remarkably acceleratesreactivity, suppresses the loss of catalytic activity as the reactionproceeds to the absolute minimum, and since the reaction is a firstorder reaction, makes it possible to obtain an ester end product havingacid value of zero. To lower the acid value, an excess of alcohol couldbe used, but OH groups remained at the ends of the product, and in priorart acidic and basic catalysts, the alcoholic groups produced, remained.Esters having a large number of terminal OH groups cannot be used forelectrical applications, as described above. An acid catalyst identicalto that of the prior art was therefore desired having excellentcatalytic activity for dehydration esterification reactions, which,although identical to the acid catalysts of the prior art, did not loseits unique activity in transesterification reactions, and which did notlose its catalytic activity even if a transesterification reaction wasperformed after esterification.

It is a further object of this invention to provide a method ofmanufacturing esters which permits elongation of reaction productscontaining ester bonds and OH groups at the ends by transesterificationreactions, and which permits manufacture of esters having a desiredpolymerization degree with a very narrow molecular weight distribution.

MEANS TO SOLVE THE PROBLEM

The first object of this invention is to provide a catalyst for anesterification reaction or a transesterification reaction, which is agel-like substance comprising a mixture of an alkoxytitanium,water-soluble polyol and water, or the reaction product thereof, whereinthe number of moles of said water-soluble polyol and said water relativeto 1 mole of titanium, is respectively 1-50 moles and 1-60 moles. Thisalkoxytitanium is preferably tetrabutoxytitanium,tetraisopropyloxytitanium or tetraoctyloxytitanium, and thewater-soluble polyol is preferably ethylene glycol, propane diol,diethylene glycol or glycerine.

The second object of this invention is to provide a method of producingan ester comprising, a first step wherein a monofunctional alcohol anddiol are simultaneously or separately added to a dibasic acid, a secondstep wherein the reaction product of said acid and alcohol produced inthe first step is separated to obtain an ester, and a third step whereinthe reaction product separated in the second step is recycled to thefirst step, 0.01-10 millimoles, preferably 0.05-5 millimoles and morepreferably 0.1-5 millimoles of the catalyst relative to one mole of acidbeing used in said first step.

The third object of this invention is to provide a method of producingan ester comprising, a first step wherein a diol is reacted with anester produced beforehand from a dibasic acid and a monofunctionalalcohol, or an ester produced beforehand from a monofunctional alcoholand diol, a second step wherein unreacted ester is separated from theproduct produced in the first step to obtain another ester, and a thirdstep wherein unreacted ester separated in the second step is recycled tothe first step, 0.05-5 millimoles of the catalyst relative to one moleof acid being used in said first step.

The term “ester” as used in the context of the present invention is aconcept including both polyesters and complex esters, as describedhereafter. Also, the term “reaction” refers specifically to only one ofesterification reactions and transesterification reactions, or to bothesterification reactions and esterification reactions. This is becausethe catalyst of the present invention is effective for bothesterification reactions and esterification reactions.

This is related to the type of dependent transesterification reaction,i.e., to the method of manufacturing complex esters and polyesters byperforming a transesterification reaction between a diol and/or itsreaction product using the catalytic function of an ester manufacturedusing an activated catalyst. The dibasic acid may be adipic acid,phthalic acid or a mixture thereof. The number of carbon atoms in themonofunctional alcohol may be 4-10, and the diol may be at least onetype selected from among 1,2-propane diol, 1,3-butane diol, 1,4-butanediol, 1,6-hexane diol or 2-ethyl-1,3-hexane diol, polyethylene glycolhaving a molecular weight of less than 1000, preferably less than 500and more preferably less than 300, and polypropylene glycol having amolecular weight of less than 1000, preferably less than 500 and morepreferably less than 300.

According to this invention, by premixing a polyol and/or water withpolyol polytitanate/polytitanic acid, or by adding and simultaneouslyreacting (esterification reaction or a transesterification reaction) apolyol and/or water to form a reaction system, it is proposed toincrease the number of active sites in the polyolpolytitanate/polytitanic acid catalyst, to prevent deactivation ofpolyol polytitanate due to esterification including active sites in theesterification or transesterification reaction, thus extending thelifetime of the active sites, and to remarkably increase the activity ofthe activated titanium catalyst. When this catalyst is used in adehydration esterification, the reaction proceeds as a first orderreaction in direct proportion to the logarithm of the acidconcentration.

This polyol water active titanium is produced by dissolving and reactingan alkoxytitanium with a polyol and water in the proportion of 1-50moles polyol and 1-60 moles water to one mole of titanium so as toobtain a gel product containing an excess amount of water which is thefeature of this polytitanate. This gel is then suspended in a solvent orthe alcohol used for the reaction, and added to the reaction system.

If this catalyst is used, as shown in FIG. 1, dehydrated esters react ina first order reaction which is much more rapid than the reactions ofthe prior art. This means that the end point of the reaction can bepredicted, and after a certain time has elapsed from the measurement, areaction product having an effective acid value of zero can be obtained.Using this catalyst, it is possible not only to obtain esters having anacid value lower than that of the acids usually used as catalysts, butthe acid value can easily be lowered with ester products having a highacid value or esters whereof the acid value has increased due todeterioration or the like.

According to this invention, the acid value of diester compounds whichare used excessively in the following transesterification reaction andrecovered, and whereof the acid value has increased due to thermaldecomposition, can easily be lowered in a short time so that they can bere-used. In other words, the diesters can be recycled.

The fourth object of this invention is to provide a method of producingan ester comprising a step of reacting a reaction product, comprising anester composition (RO(COACOOX)_(n)H) (n≧1) formed from the reaction of adibasic acid (HOOCACOOH), diol (HOXOH) and terminal alcohol (ROH), inthe presence of a catalyst according to claim 1 or 2 under a reducedpressure of 100 mm Hg or less. It is preferred that this reactive estercomposition is the reactive ester composition (RO(COACOOXOH) wherein thedibasic acid (HOOCACOOH), diol (HOXOH) and terminal alcohol (ROH) arepresent in the molar ratios 1:1:1.

It is also preferred that this reaction product contains an estercompound represented by the general formula:R′O(COACOOXO)_(n)COACOOR′(in the formula, R′ are respectively alkyl groups which may be identicalor different, and may be identical to the aforesaid R).

This active titanium catalyst has catalytic activity for bothesterification reactions and transesterification reactions, and as ithas a superior activity for esterification reactions in particular, usecan be made of this property to produce and react an ester alcohol andthe aforesaid esters in an esterification process, which is the fifthobject of this invention.

Specifically, when the dehydration esterification which is the firststep of this invention is performed using the active titanium catalystcomprising a dibasic acid, diol and monofunctional alcohol, the requiredamounts of monofunctional alcohol (R) and diol (X) are distributed andcontinuously introduced into the reactor so that the production ofdiester (RAR) is suppressed as far as possible, and the conditions areadjusted so that the complex ester (R(AX)_(n)AR, n≧1) and ester alcohol(RAX) can coexist in the reaction system. In other words, in thisesterification reaction, if a high concentration of the alcohol (R) isintroduced, the undesirable diester (RAR) is produced. Due to theproduction of this undesirable diester (RAR), the excess amount (ofalcohol) must be suppressed to the degree at which the ester alcohol(RAX) can coexist with the complex ester.

Regarding the addition of alcohol, if the excess amount is reduced,there is the problem of the addition concentration. Hence, when thedibasic acid (A) and diol (X) are reacted, it is preferable to add thealcohol (R) a little at a time, and to reduce the reaction temperatureto 150-165° C. In a reaction using adipic acid (A), at this stage, thereaction proceeds at a sufficient rate even without a catalyst. Therequired amount also depends on the extent of the reaction. In themanufacture of the target product R(AX)_(m)(AX)_(n)AR (m≧0, n≧1), anexcess amount of the alcohol (R) is used compared to the stoichiometricamount required to obtain R(AX)_(m)(AX)+R(AX)_(n−1)AR to perform theesterification reaction. The amount of the alcohol (R) is excessiverelative to the target product, but the stoichiometric amount of theesterified product including the diol is obtained even if the wholeamount is reacted, so from this viewpoint it is not excessive. Further,as water is excluded from the reaction system and the reaction takesplace under anhydrous conditions, quantitative control of the reactionof the lower diol (X) is not easy. The diol component is removed fromthe reaction system corresponding to the reaction rate and waterdistillation rate, so it fluctuates largely depending on reaction molaramounts and it is difficult to perform a stoichiometric reaction, butthe reaction amounts of each component must be controlled. If thealcohol reaction amount is insufficient due to the distillation of thediol, the alcohol amount will be insufficient even if the amount of thealcohol (R) is controlled, so the acid value does not decrease, thetransesterification reaction of the next step does not take place, andlow volatility components in the reaction product including esteralcohols, increase. On the other hand, if the addition rate of thealcohol (R) is too high or an excess amount is used, the productionamount of diester (RAR) increases, so that not only does the amountremoved increase, but the polymerization degree of the reaction productincreases correspondingly and a reaction product having the targetpolymerization degree cannot be obtained. Due to the use of the highlyactivated catalyst of this invention, the reaction between very smallamounts of acid and alcohol is a first order reaction, and the reactionproceeds rapidly even with minor components. Hence, a quantitativereaction can be performed, and esters ranging from polyesters of highmolecular weight to complex esters of low molecular weight having atarget polymerization degree with a narrow distribution, can now bemanufactured.

Next, a transesterification reaction which is the second step, isperformed. Specifically, a complex ester (R(AX)_(n−1)AR, n≧1) and esteralcohol (R(AX)_(m)AX) are reacted to produce a desired ester(R(AX)_(m)(AX)_(n)AR). When m in the ester alcohol (R(AX)_(m)AX) islarge, the ester is a polyester, while for a complex ester, it is analcohol ester (RAX) corresponding to m=0.

Thus, esters having a molecular weight distribution of 2 or less can bemanufactured. In this case, the molecular weight distribution refers toPw/Pn (Pw is weight average polymerization degree, Pn is number averagepolymerization degree).

As a result of the method of this invention, an excellent molecularweight distribution is obtained, and in the complex esters (R(AX)_(n)AR,n≧1) which have a low polymerization degree, terminal alcoholpolyesters, and diester (RAR) side products corresponding to n=0, whichwere the most difficult problem to overcome, are now suppressed.

If the method of this invention is not adopted, the introduction amountsof alcohol (R) and diol (X) in the esterification reaction are notcontrolled, or a prior art catalyst without strong esterification andtransesterification catalytic activity is used, it is difficult toobtain the product in a stable process.

Using the method of the present invention, polymerization of the complexester produced is suppressed, and the molecular weight distribution isnarrow. In addition, the acid value can be reduced, transesterificationis easy and a product having a desired molecular weight can bemanufactured. The rated values of the polyesters already on the marketcan thus be considerably improved. In complex esters, high molecularweight compositions decrease, the viscosity of the product falls anddiester side products decrease, so superior complex esters can bemanufactured. It is expected that these will be useful as plasticizersof low viscosity having superior plasticizing properties, which do nothave any marked volatility, and which are environment-friendly.

When an active titanium catalyst is used, its catalytic activity mayfall. This is probably due to absorption or reaction with the titaniumcatalyst depending on the type of polyol component, covering of activesites and suppression of acid absorption leading to decline of catalyticactivity. When ethylene glycol is used for catalyst activation, thedecline of activity is relatively small, so this catalyst therefore hasexcellent activity and retained its activity. If another diol componentsuch as propane diol is used in the activated catalyst to avoidintroduction of ethylene glycol in an esterification reaction between adiol and an acid, the activity may decline at the end of the reactioneven though some diol apparently remains. In a reaction system where theactivity had declined due to the diol component, the same reaction ratecannot be obtained even if activation is performed using the same diolcomponent. Even in this case, using ethylene glycol-water, the catalystmay be adjusted by a solvent, alcohol or a diol. However, if analkoxytitanium is dissolved to prepare a catalyst and this is thenadded, it exhibits excellent activity and the acid value can theneffectively be lowered.

Specifically, the fifth object of this invention is to provide a methodof producing an ester comprising a step of a dehydration esterificationreaction and a following transesterification reaction of a dibasic acid,diol and monofunctional alcohol using the catalyst. This active titaniumcatalyst is a gel comprising an alkoxytitanium, water-soluble polyol andwater mixture or the reaction product of this mixture, the proportionsof water-soluble polyol and water being 1-50 moles and 1-60 molesrelative to one mole of titanium. The required amounts of saidmonofunctional alcohol and said diol are distributed and continuouslyintroduced into a reactor over the whole period of the esterificationreaction.

It is preferred that the dehydration esterification reaction isperformed under conditions such that a complex ester and ester alcoholare produced and coexist together.

Further, when the target product of the manufacturing method of thisinvention is represented by R(AX)_(m+n)AR (m≧0, n≧1, A is a dibasicacid, X is a diol and R is a monofunctional alcohol, the reactive groupsand ester bonds being omitted), the amount of said monofunctionalalcohol (R) used in said dehydration esterification reaction is obtainedby adding 0.2-2.0 times, particularly 0.5-1.0 times the differencebetween the amount required to obtain R(AX)_(m)AX+R(AX)_(n−1)AR as theproduct of the dehydration esterification reaction and thestoichiometric amount required to obtain R(AX)_(m+n)AR, to thestoichiometric amount required to obtain R(AX)_(m+n)AR.

In this case, the aforesaid difference R is equal to one mole.R(AX)_(m)AX may be considered as separate parts R(AX)_(m) and RAX, andthe stoichiometric amount in this case is increased by 2R so that 2R isused as the excess amount. The excess amount is determined by the ratiom/n of the polymerization degrees of the target substances. It may be anamount less than 1 to an amount of several times, but if it is less than0.33, the molecular weight distribution widens, and it is less than 0.2,its proportion is low and its effect is unclear. If it is too large, RARincreases so there is no effect. It is therefore preferred to use0.2-2.0 times an amount relative to the difference from thestoichiometric amount, as the excess amount.

By distributing this amount and introducing it continuously into thereactor, the aforesaid dehydration esterification reaction takes placeunder conditions wherein a complex ester and ester alcohol are producedtogether.

Further, according to this method, the molecular weight distribution ofthe ester produced is 2 or less, so a complex ester having a narrowmolecular weight distribution can be manufactured.

Herein, the term “esters” is used in the sense of including bothpolyesters and complex esters which are described in detail hereafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a variation of concentration in the esterification reactionusing the active titanium catalyst of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The catalyst of this invention is a mixture of an alkoxytitanium,water-soluble polyol and water, or the reaction product of this mixture.

Herein, alkoxytitanium includes tetrafunctional tetraalkoxytitaniumssuch as tetrabutoxytitanium and its tetramers,tetraisopropyloxytitanium, tetraethoxytitanium andtetraoctyloxytitanium, alcohol solutions such as titanium trichlorideand titanium tetrachloride and compounds known as orthotitanic acidesters, but tetrabutoxytitanium, tetraisopropyloxytitanium ortetraoctyloxytitanium are preferred, and tetrabutoxytitanium is morepreferred. There is no particular limitation on the water-soluble polyolprovided that it is a water-soluble compound having two or more hydroxylgroups, but ethylene glycol, propane diol, diethylene glycol orglycerine is preferred.

In this invention, the proportion of water-soluble polyol of thisalkoxytitanium is preferably 1-50 moles, preferably 5-20 moles and morepreferably 8-15 moles, and the proportion of water is 1-60 moles,preferably 4-40 moles and more preferably 10-20 moles relative to onemole of titanium in this alkoxytitanium.

These may simply be mixed together, heated together or dissolved in asolvent, and there is no limitation on the mixing sequence.

The mixture of alkoxytitanium, water-soluble polyol and water reacts atroom temperature to form a gel.

It appears that this structure has a spherical form containing water onthe inside, and is coated with a polyol polytitanate. It is also thoughtthat a large number of OH groups are present on the outer surface whichaccounts for the catalytic activity.

As is known from the prior art, when an alkoxytitanium is mixed with apolyol, a polyol polytitanate is produced, whereas, when analkoxytitanium is mixed with water, it becomes polytitanic acid, and ifmethanol and water are added to and reacted with it, there are OH groupsappeared on the surface which develop catalytic activity. However, thecatalyst of this invention not only has a much higher catalytic activitythan the polyol polytitanate/polytitanic acid of the prior art (FIG. 1),but practically suffers no catalyst deterioration over time. Hence,catalyst of this invention has an effect which could not be envisaged inthe prior art. It is thought that this excellent result is due to theunique structure described above.

According to this invention, complex esters and polyesters can bemanufactured by esterification reactions, and mainly,transesterification reactions, using the titanium catalyst of thisinvention. However, it may be used for manufacturing only theesterification reaction products of the first step, in which caseproduct can be obtained simply by adding water and filtering off thetitanium. Concerning transesterification reactions, the reaction moleratio of the diols and esters used is important. The larger the amountof diesters, the more lower viscosity products of a low polymerizationdegree tend to be obtained, and conversely, the larger the molar ratioof diols, the more products of high polymerization degree tend to beobtained. The reaction molar ratio is determined according to thepolymerization degree of the target product, and diol diesters are alsoused as the diol component.

Due to this structure, an excess of diester, for example 4 molesrelative to 1 mole of diol, is used to obtain a low viscosity product.Two moles is an excess, and even if a reaction amount of 2 moles or lessis used, the amount of unreacted diester remaining must be recycled. Athigh temperature, apart from the coloration due to the catalyst,volatile acids such as for example phthalic anhydride are produced bythermal decomposition, so a reduced pressure concentration device whichhas a sufficiently large heating amount should be provided if possible,and it is more preferred that this should have continuous operation.

In the ester manufacturing method carried out by the Inventor so far,the best way of controlling the molecular weight distribution was togradually add an octanol, which is a terminal alcohol, and in thetransesterification reaction, if the reaction is performed whilegradually adding a diol, the proportion of the transesterificationreaction due to the octanol can be reduced and a product close to thetarget product can be obtained. However, the higher the polymerizationdegree, the less it is possible to avoid the effects of thetransesterification reaction due to the octanol. As a result, themolecular weight distribution of the target product contains a highproportion of low polymers but also contains high polymer components(wide molecular weight distribution).

The type of complex ester products obtained in the dehydrationesterification reactions and transesterification reactions of complexesters depends to some extent on the type of components. Ethylene glycoland diethylene glycol are additives with a poor water resistance and canbe destroyed by microorganisms. Ordinary diols having 3-8 carbon atomsand polypropylene glycol have fairly similar properties, and the diolside chain improves water resistance (Japanese Patent Application PublicDisclosure Hei 6-172261).

In general, a straight chain adipic acid is used as the acid, butunsaturated acids or aromatic acids are also used. With phthalic acids,the viscosity rapidly increases as the degree of homopolymerizationincreases, but if they are partially mixed for use as plasticizers, aproduct having excellent physical properties such as water resistanceand resistance to migration, is obtained. Monohydric alcohols having aterminal group are not limited to the octanol of the embodiment, andother alcohols having four or more carbon atoms may be used. In loweralcohols, water resistance is poor, and the higher the alcohol, the moreevident the effect of the long chain is. As an example of another typeof alcohol, polyethylene glycol monoalkylethers have been noted tosuppress the growth of fungii.

The reaction process will now be described. As mentioned above, dioctyladipate which is a diester of adipic acid and a diol ester aremanufactured separately. Adipic acid is added to the diester to reducethe proportion of retroreaction wherein the target is n=2, but n=1 alsooccurs as a side product.

In this reaction, the octanol produced in the transesterificationreaction reacts again, and if the reaction proceeds still further, itmay lead to removal of the diol.

Thus, the purpose of the addition reaction is to reduce the proportionof retroreaction. Polyesters of any desired polymerization degree can beobtained by adjusting the molar ratio of diol diester and diester, whichis useful for example to obtain polyesters of high polymerizationdegree.HOCOACOOH+2HOXOH→HO(XOCOACOO)XOHHO(XOCOACOO)XOH+nROCOACOOR→RO(COACOOXO)nCOACOOR+ROCOACOOR

These can be added to the reaction system separately, which is useful toobtain a hetero complex ester, but the diol diester may also added inadmixture. With a hetero complex ester, a hetero dibasic acid diester isproduced as a side product in the retroreaction and must be separated,so it is advantageous to add the diester and perform thetransesterification reaction while removing octanol under reducedpressure. A different diol diester may be added alone or in admixture,the molar ratio of the diol diester and diester determined, and the dioldiester added to the diester to carry out the transesterificationreaction and obtain the product.nHOCOACOOH+C₆H₄(CO)₂O+2n+1HOXOH→nHO(XOCOACOO)Nxoh+HO(XOCOC₆H₄COO)nXOH→+2n(n+1)ROCOACOOR→RO(COACOOXO)_(n)(COC₆H₄COOXO)_(m)COACOOR+ROCOACOOR

In this addition reaction, even if it is attempted to perform theaddition rapidly and remove alcohol, if the octanol produced is notremoved from the system within sufficient time, the aforesaid diolremoval reaction occurs or different acid diesters are produced, so themolecular weight does not increase. On the other hand, when a homocomplex ester is manufactured, a transesterification reaction may beperformed while heating the mixture, and the reaction carried out whileadding the diol and diol diester. In another method, a mixture of anester alcohol and a diester is prepared by a dehydration esterification,and a transesterification reaction is then performed (Japanese PatentNo. 2517245). In this case also, products having differentpolymerization degrees can be obtained by varying the molar ratio ofester alcohol and diester.2n+1ROH+n+1HOCOACOOH+HOXOH→ROCOACOOXOH+nROCOACOOR→RO(COACOOXO)_(n)COACOOR+ROCOACOOR

In this reaction, an addition esterification reaction can subsequentlybe performed to obtain the target product.

Specifically, a mixture of the ester alcohol and diester is prepared(Step A), the diester to be recycled is added (Step B), the temperatureis temporarily lowered to about 140° C. and the reaction molar ratio isadjusted, and the transesterification reaction (Step C) is then startedby increasing the degree of pressure reduction while gradually raisingthe temperature. By maintaining conditions of 200° C., 25 mm Hg, thetransesterification reaction takes place and after removing sufficientalcohol, the addition esterification reaction of the next step (Step D)is performed. The feature of this two-step transesterification reactionis as follows. In the esterification reaction (A) for manufacturing theester alcohol and ester, corresponding to the reaction molar ratio, thediol component represents an excess of alcohol, and when the diester ismanufactured, about 20% excess alcohol is used. Consequently, a step isrequired to remove the excess alcohol prior to the transesterificationreaction. However, the esterification reaction (C) can be performedwithout any excess alcohol at all.

In the following addition esterification reaction (D), whenmanufacturing a hetero complex ester, if a retroreaction occurs and diolis removed, even if the diol participates in further reactions, dioctylphthalate which is a side product mixes with recycled diester, so a stepis required to separate and remove it. In practice, in a batch reaction,diester which is produced as a side product cannot be re-used, so thecost increases due to the side product diester, and the manufacturingprocess is not profitable. If the complex ester is required to havewater resistance, the diol and hetero complex ester are expensive, andin the case of a hetero complex ester, re-use of the side productdiester was a problem. In this addition transesterification reaction,the reaction is performed by the diol diester of phthalic acid. Areaction due to dioctyl phthalate occurs due to transesterification inthe mixed liquor. This is a transesterification, or an ordinarydehydration esterification reaction followed by a transesterificationreaction to reduce the volatile component, wherein a step (E), furthersimplifying the structural formula and abbreviating the different acidsas A, P, alcohol as O and diol as X, occurs with a considerably highprobability in the presence of a titanium catalyst. This reaction can beprevented by an addition transesterification reaction, so the sideproduct diester can be recycled and re-used.3ROH+HOCOACOOH+HOXOH→(A)ROCOACOOXOH+ROCOACOOR→+ROCOACOOR(B)→RO(COACOOXO)nCOACOOR+ROCOACOOR(C)→+HO(XOCOC₆H₄COO)XOH→(D)RO(COACOOXO)_(n)(COC₆H₄COOXO)_(m)COACOOR+ROCOACOOROAO+HOXPXOH+2OAO+O→OAXPO+HOXAO+OAO→OAXOH+OPO+OAXAO→OPO+OAXAXAO(E)

Regarding the product of a sequential addition esterification reaction,if an excess of octanol is used in the transesterification reaction, anester alcohol is produced so it is necessary to perform atransesterification at the end of the reaction, and this process can beused.

It is a feature of the catalyst that the reaction rate is greatlyenhanced, and the reaction proceeds as a first order reaction. Thismeans that a reaction takes place even between very small amounts ofacid and alcohol, and that a reaction takes place with only a smallexcess provided that it is a stoichiometric excess. During theesterification of a dibasic acid, diol and terminal alcohol, consideringthe intermediate products of an ester alcohol and a diester, an excessof ROH is theoretically necessary, and if the esterification reactioncan proceed sufficiently with this excess alone, the excess can beremoved by a transesterification reaction.

Experimental results show that due to the use of the catalyst of thepresent invention, the reaction proceeds at a sufficient reaction ratewith the stoichiometric excess, and target composition esters with a lowacid value and excellent molecular weight distribution can bemanufactured. It is thus possible to prevent the excess alcohol which isgenerally used from acting on the product, leading to atransesterification reaction, and polymerization (isomerization) todiesters and esters of high polymerization degree, and as a result,esters having a superior composition can be manufactured.ROH+HOCOACOOH+HOXOH+ROH+HOCOACOOH+HOR→ROCOACOOXOH+ROCOOACOOR→ROCOACOOXOCOACOOR+ROH

In complex esters of low polymerization degree and isomeric complexesters, concerning the use of excess diol and terminal alcohol, thepurpose of the reaction can be achieved assuming a complex ester havingn greater by 1 corresponding to the use of excess diol.ROH+nHOCOACOOH+nHOXOH+HOCOACOOH+2ROH→RO(COACOOXO)_(n)H+ROCOACOOR(n1ROCOACOOXOH+ROCOACOOXOCOACOOR)→RO(COACOOXO)_(n)COACOOR+ROH

Due to the use of this excellent catalyst, with polyesters, astoichiometric composition can be reacted in close to the stoichiometricamount, so a superior composition can be obtained. However, it iseffectively impossible to carry out the transesterification reactionquantitatively in the proportion of one diester for one ester alcohol.Thus, polyesterification takes place, and correspondingly, unreacteddiester remains so that side products cannot be prevented.

With polyesters, transesterification occurs with the polyester, so sideproduct diesters can be ignored and a product having an excellentdistribution can be obtained. With lower complex esters, a manufacturingmethod is adopted wherein side products are reduced by making thetransesterification reaction a reaction with a complex ester. It isneeded to treat the diesters which are produced as side products in thereaction as complex esters in the aforesaid two-step transesterificationreaction, and use unreacted diester as a starting material for therecycling reaction.

When complex esters are used as plasticizers, excellent properties areobtained by using hetero complex esters. There is no particular need toattain high molecular weights, and superior plasticizer properties areobtained the lower the viscosity is. In the case of low volatilityplasticizers used for electrical applications of the prior art,polyethylene is used in conjunction with other resins, so a plasticizerwas desired with little migration within the resin or to other resins.For this purpose, the molecular weight is increased, but as it is fairlydifficult to control the molecular weight distribution, low molecularweight fractions are removed, designers aim for a higher molecularweight than is necessary, and substances having a molecular weight inthe range 2000-4000 are used. It was thus difficult to reduce itsviscosity and acid value. Judging from the experimental results obtainedby the Inventor so far, not only a straight chain part but with partialuse of phthalic acid, a scissors-shaped part, is formed in the molecule,and it is disclosed in Japanese Patent Application Public Disclosure Hei8-157418 that as a result, there are few migrations not only withinvinyl chloride (transitions from a high density to a low densityplasticizer), but also to polyethylene. In addition, regardingplasticizer applications, low molecular weight adipates are hydrolyzedwhen used under high humidity and their surface whitens, so waterresistance was required. With this objective, properties can be improvedby incorporating 0.3 or more units of phthalic acid. As a plasticizerfor polyvinyl chloride, dioctyl phthalate has been used and it hasexcellent properties, but in outdoor applications, it evaporates due toits vapour pressure. In this regard, complex esters have excellentproperties as non-volatile plasticizers, and exhibit identicalplasticizer properties corresponding to the viscosity of theplasticizer. The usage proportion of plasticizer, having an identicalhardness to that of 50 parts of DOP, is 52 parts or less for a complexester having a viscosity of 500 centipoise and polymerization degree ofup to 5, and this number drops to 46 for a polymerization degree of 1.As the adipic acid content increases, low temperature propertiesincrease and there are also cold resistance applications, however theincrease in polymerization degree is adversely affected. Low molecularweight complex esters exhibit a higher plasticity, but it is difficultto manufacture them only with n=1, so they are manufactured selectivelyfor plasticizer applications according to the ease of manufacture and amanufacturing cost corresponding to the desired properties.

Complex esters have the general formula: ROCOACOOXOCOACOOR (in theformula, R is an alkyl group of a terminal alcohol, A is mainly an acidresidue of adipic acid (—CH₂CH₂CH₂CH₂—), and X is an alcohol residue ofthe diol used (e.g., —CH₂CH(CH₃)—: propane diol)). They have been usedas low temperature lubricating oils, and it is thought that, because theesters of this invention have a low acid value and low OH value, whenusing a diol component which has low temperature properties and adipicacid, they exhibit excellent characteristics for their intended use. TheInventor discovered that even if it was intended to manufacture complexesters which are generally manufactured as composite esters, mixturesare obtained as represented by the integer n in RO(COACOOXO)_(n)COACOOR.In particular, in the manufacturing method, a composition was obtainedcomprising plural substances in different proportions, and theirproportion decreased as the value of n increased, differentiating itfrom composite esters. Therefore, the molecular weight shows the averagevalue for the mixed composition, e.g., 1.5 represents an equimolarmixture of n=1 and n=2. From experimental results obtained previously,it has been found that even if it was attempted to produceRO(COACOOXO)COACOOR, if one mole of RO(COACOOXO)₂COACOOR was produced asa side product, one mole of ROCOACOOR was produced corresponding to theincrease in the value of n. Using this fact, if the number of moles ofROCOACOOR, obtained by subtracting the weight of yield product from theweight of target product, is calculated, and the value of n in theproduct RO(COACOOXO)_(n)COACOOR is calculated assuming that the numberof moles of target product obtained by subtracting this number of moles,is produced, the average molecular weight of the product can becalculated. If the molecular weight of the complex ester is calculatedin this way, the reaction can be treated quantitatively. Likewise, thepolymerization degree of diol diesters is identical in principle. Thevalue obtained by subtracting the stoichiometric amount shown in ( ) ofadipic acid ester from the weight of the reaction product of dioldiester represented by HO(XO)COACOO)_(n)XOH and dividing by themolecular weight of HOXOH, represents the number of moles of theproduct, and assuming that its inverse represents the value of thepolymerization degree n, the molecular weight can be calculated. Itshould be noted that in the examples, empirical formulae are shown.Adipic acid is represented by A, phthalic acid by P, and the diolcomponent by HOXOH or X. Depending on the type, propane diol is shown byX_(p), dipropylene glycol is shown by X_(DP), and the symbol X_(2E) isalso used. Also, terminal alcohols are represented by the symbol O. Thepolymerization degree is an important factor in the composition, so ithas been represented by a numerical suffix following ( ).

According to this invention, if phthalic anhydride is used as thedibasic acid, the reaction is started with one mole of this and one moleof a diol, and one mole of a monofunctional alcohol is added. In thisesterification, an ester alcohol is obtained. A complex ester notcontaining (PX)_(n)of high molecular weight can then be manufacturedusing this ester alcohol, and performing an addition transesterificationreaction under reduced pressure. In the transesterification reaction, acompletely equimolar reaction is impossible, so it is preferred toperform a quantitative reaction using a large amount of diester as faras possible. In the transesterification reaction, RPXOH is writteninstead of the RAXOH of (1), meaning that phthalic acid is used insteadof adipic acid.

Herein, if ROH produced by heating the reaction mixture is removed, theproduct is obtained (Japanese Patent No. 2517245), but as aretroreaction occurs at the same time, (PX)_(n) with n=3 or higher isproduced as a side product when phthalic acid is used, and the viscosityincreases.

According to this invention, the transesterification reaction is carriedout under reduced pressure, preferably less than 100 mm Hg, morepreferably less than 30 mm Hg, still more preferably within the range0.2-25 mm Hg, and most preferably within the range 0.5-2 mm Hg. Thereaction temperature is a high temperature in the vicinity of theboiling point of RAR, i.e., 160-250° C., but preferably 180-220° C., andit is preferred to carry out the transesterification by adding thecomponents a little at a time.

If the number of moles of the diester RAR used in this reaction is 2 orless, the polymerization degree of the product is 2 or more, so it ispreferred to use 2 moles or more to obtain a low viscosity product, butif it is more than this, the amount of RAR used for recycling increasesand efficiency falls. If it is less than 1.5 moles, the product has ahigh viscosity and the advantage of this invention is no longerobtained. Regarding the composition of the product obtained, the yieldis subtracted from the stoichiometric amount, and assuming that thenumber of moles of RAR in this number of grams had no effect on thereaction, the number of reaction moles and reaction proportion arecalculated, and the inverse is calculated as the polymerization degree nof (PX)_(n). (PX)₂ does not necessarily mean PXPXP, and in thisreaction, it is thought to exert no influence on the reaction of ROH.The unit of the product has the structure PXAXP, which is thought to bethe reason why a low viscosity product is obtained.

With adipic acid, unlike the reaction of the anhydride of phthalic acid,a selective reaction cannot be performed, but if the reaction betweenthe diol and acid is given priority and a terminal alcohol is added,side production of the diester RAR is reduced. However, unless it isdesired to selectively manufacture a bis compound of a complex esterwith low n, it is better to use the components without modificationwhich presents no problem for calculation of the polymerization degree.The number of moles of R(AX)nOH, R(PX)nOH may be computed and theirproportions in the reaction calculated, assuming that the reactionproduct is a volatile component under reduced pressure, by removing thetoluene used as an azeotropic material, unreacted terminal alcohol and1-octanol, dividing the difference between the weight of the product andthe calculated amount by the molecular weight of octanol to calculatethe number of moles, and subtracting this from the usage amount. Theinverse of this proportion is calculated as the polymerization degree nof (AX)_(n). Although there may be differences in the reaction, thevalue is approximately 1.1-1.3, and it may be used to calculate theaverage molecular weight after removing ROH, but it may also be usedwithout removing ROH and taking n=1 for the mixture.

With adipic esters, a retroreaction can partially be performed so that acomposition having a wide molecular weight distribution is obtained, butby carrying out an addition transesterification under reduced pressure,higher molecular weights can be obtained. In this way, a polyesterhaving the target polymerization degree can be manufactured as a lowalcohol terminal product with a low acid value. Regarding the molecularweight distribution, a transesterification reaction takes place in theterminal part, but a transesterification reaction also occurs in theinner part of the polyester, and in the second position from the end,the retroreaction represented by equation (4) also takes place.Consequently, it is unlikely that a perfectly normal distribution wouldbe obtained, but as the retroreaction due to ROH is controlled, theproduct probably has a molecular weight distribution close to a normaldistribution.

In Example 16 described later, a polyester reaction was carried out toobtain a molecular weight of 3500 from a complex ester having apolymerization degree of 4, which was obtained directly from asequential addition dehydration esterification reaction. It was notedthat there was no side production of the low molecular weight diesterRAR, therefore there was no need to remove a low molecular weight partby high temperature distillation after polymerization had taken place.On the other hand, in the reaction with the diol (Example 5), about 20percent of RAR remained unreacted although twice the number of moles ofR(AX)OH, the ester alcohol, was used, so it was calculated that themolecular weight increased to about 20% higher than that of the targetcomposition.

It is well known that, among complex esters, water resistance improvesby using a hetero complex ester. This objective can be achieved bymanufacturing R(AX)_(n)OH and R(PX)_(n)OH separately or in admixture,determining the respective addition amounts depending on the targetcomposition, adding different components before or after, and performinga transesterification reaction. A further feature of this invention isthat the molecular weight and composition can be easily controlleddepending on the purpose, and in particular, a substance can be providedwherein the acid value and alcohol value are effectively zero, and thealcohol terminal polyester with a limited molecular weight distributioncan be provided.

The ester structure manufactured as the object of this invention is thereaction product represented by the following reaction equation andgeneral formula (A):R+n(A+X)+A+R→R(AX)_(n)AR  (A)

Herein, R (i.e., ROH) is a monofunctional alcohol or 4 or more carbonatoms having a straight chain or side chain, and in the examples,2-ethylhexanol was used as it is generally used in the prior art. Thealcohol is not limited to an alkyl alcohol. In ether alcohols referredto as ethylene glycol monoalkyl ethers, alcohols having different alkylgroups are used for antiseptic purposes, and ether glycols based ondiethylene glycol may also be used. The dibasic acid represented by A(i.e., HOCOACOOH) is not limited to adipic acid or phthalic acid, butmay also be an unsaturated acid such as succinic acid, glutaric acid,suberic acid, or partially, terephthalic acid, its hydrogen additionproduct or maleic anhydride. Two or more of these may be used inadmixture. The diol represented by X (i.e., HOXOH) is selected from theviewpoint of low temperature properties required of a plasticizer andcost. Straight chain diols having 2-6 carbon atoms, or diols having aside chain such as 1,2 or 1,3-butane diol, 2-ethyl, 1,3-hexane diol, areused depending on the particular properties it is desired to stress, andether alcohols such as di(poly)ethylene glycol, dipropylene glycol, canbe used according to the purpose including hydrophilic affinity.

In the polyester structure of the prior art, in particular, compositionwas a problem and it was difficult to lower the acid value correspondingto the polymerization degree, hence in high molecular weight esters, theeffect of transesterification was small, lower ester alcohols remained,and a polyester having an undesirable distribution was obtained.

In these terminal alcohol polyesters, the length of the chain structurecorresponds to the molecular weight. When rigidity is required, shortstraight chain units are used, and when flexibility and water resistanceare required, a chain diol having a side chain or a mixture of theseunits are used. They can be used as materials for higher polymerpolyesters, and are useful as plasticizers corresponding to theirviscosity and polarity. Polyethylene adipates of biterminal alcoholsshow excellent properties as plasticizers for polyethylene terephthalate(PET), and by making use of transesterification reactions, they can beused as polymerizable materials for biodegradable plastics. Complexesters are slightly different in the terminal alcohol, but theirmolecular weight is at least about 500 for n=1, and it is known thatwhen they are used as plasticizers for polyvinyl chloride, they do notevaporate at all even if used continuously at 80° C. for 1 month. Theremoval of dibasic acid diesters which are also present as side productswas a problem, and it was questionable whether or not this sideproduction could be reduced to a negligible level. As they cannot beproduced quantitatively, re-use of the side product diesters isrequired.

Use of Excess Alcohol in Esterification Reaction

If an excess of alcohol relative to acid is not used, as can be seenalso from the equilibrium theory of the chemical reaction, it is notpossible to make all the acid react without fail, however in thesereactions, the excess amount must be reduced to the absolute minimum.Therefore, according to this invention, the reaction product is obtainedby performing a reaction which partially goes through an ester alcohol.

In the aforesaid reaction equation (A), in the process R+A+X+A+R→RAXAR,the reaction takes place between reaction amounts of 2R and 2A, but ifthe reaction is partly designed so that {R+A+X}+{R+A+R}→RAX+RAR, more Rcan be used in a reaction between reaction amounts of 3R, 2A and X. Ifthis reaction is performed, the preceding reaction also takes place atthe same time, so there is no guarantee that all the product will be RAXeven if an excess of R is used. In general, the reaction proceeds morerapidly with a monofunctional alcohol than with a diol and the majorityof the product will be RAX+RAR, but due to the transesterification ofthe last step, RAX loses R, and the reaction is

RAX+RAR→RAXAR+R. This reaction cannot be carried out quantitatively, thesequential reaction RAX+RAXAR→RAXAXAR proceeds as a dependent reaction,unreacted RAR remains and the value of n in R(AX)_(n)AR increases.Therefore, a product closer to the target substance is obtained thehigher the molecular weight is, but with a lower complex ester,sequential reactions cannot be prevented. This means that pure RAXARcannot be manufactured, but it is possible to design the reactionconditions so that the excess amount used is the absolute minimum. Next,when it is desired to make n=1, the value of n increases, so an excessamount of X is used in order to make the value of n large beforehand. If2X is used, the reaction takes place with RAX+RAX+RA which is a reactionbetween 3R+3A+2X, and compared to when n=1 (1.5 moles of RAXAR), i.e.,3R+3A+1.5X, 0.5X more alcohol is used. n=1 cannot be produced, but bydesigning the reaction so that a higher value of n is obtained, anexcess of alcohol can be used. Hence, the reaction takes place without adrop in reaction rate, and by selecting the reaction conditions, a dropin catalytic activity and a drop of reaction rate due to insufficientalcohol are prevented, and a product close to the target product can bemanufactured.

Manufacture of Polyester

As a means of controlling molecular weight, it is important to controlthe reaction between the diol and dibasic acid unit. Depending on thediol component, it boils off together with water in the dehydrationesterification reaction. Therefore, it is necessary to adjust thecomposition in the middle of the process. Further, it is possible thatthe composition will vary if the reaction is carried out in one step.The required amount of monofunctional alcohol to perform molecularweight control is used, but to obtain a homogeneous product, it ispreferred to perform the polyesterification by adding half of the acidin small amounts prior to the reaction, and then adding the remaininghalf. In the case of an addition reaction between equivalents, the acidvalue does not fall sufficiently. Thus, the activated catalyst andexcess amount of diol are added together when 90-95% of the reaction hastaken place, and the reaction is then continued. Using the activatedcatalyst, the logarithm of the unreacted amount of acid calculated fromthe acid value is first order with respect to time, so the reactionendpoint can be predicted. On the other hand, as regards catalyticactivity, the diol component may block the active sites which rendersthe catalyst inactive. Therefore, it may be necessary to add theactivated catalyst while verifying the remaining amount of diol. Theinactivation varies depending on the diol component. With ethyleneglycol, the inactivation time is longest, and the concentration ratiowith water during activation also has an effect. After reducing the acidvalue sufficiently using an activated catalyst, a transesterificationreaction is performed between the ester alcohol produced by the excessdiol used as an activation agent and polyester. A distillation apparatusis installed in the reactor, volatile components are removed underreduced pressure, the temperature is raised to 180-200° C., the degreeof pressure reduction is increased to about 0.3 mm Hg, and the octanolproduced (terminal alcohol component) is removed. Molecular weights arecalculated beforehand including the diol component which is addedtogether with the catalyst, and the reaction takes place in thecompositional proportions of the three components. The correspondingterminal alcohol is then added, and an addition reaction performed. Itis advantageous if the diol amount added last, is added together withthe catalyst, and the effect of a small amount is larger the higher themolecular weight of polyester is. Even if only a very small amount ofdiol is used, the average molecular weight prior to transesterificationmay reach twice that subsequent to transesterification. Thetransesterification reaction takes place at the same time, and theexcess of diol component used in the dehydration esterification reactionis probably in the form of an ester alcohol. The corresponding terminalalcohol is recovered in the transesterification reaction of the nextstep, and the ester polymerizes.

If the reaction molar amount is 2n moles and the excess diol is X_(E),using one mole which is equivalent to ( 1/2n), the intermediate productsand product are given by the following equation.2(n+1)A+2nX→2nAX+2A→addition polymerization esterification of R →fullesterification intermediate step {2R(AX)_(n)AR}Next, addition of X_(E) andcatalyst→R(AX)_(n)AX_(E)+R(AX)_(n)AR→transesterificationreaction→R(AX)_(n)AX_(E)(AX)_(n)AR.

The molecular weight after transesterification increases correspondinglywith the molar ratio of the number of moles of esterification reactionproduct and the number of moles of excess diol used, and a targetproduct whereof the average polymerization degree varies according toits precision, is obtained.

Manufacture of Dibasic Acid Complex Ester

Describing now the manufacture of a complex ester of a dibasic acid suchas adipic acid, it is very difficult to selectively perform a reactionbetween an acid and a diol, but it is most important to manufacture theester so that no free acid remains. As it is effectively impossible tomanufacture only a complex ester having n=1, the reaction is performedunder the aforesaid conditions. Equimolar amounts of the dibasic acidand diol are reacted together under as mild conditions as possible.Fortunately, dibasic acids such as adipic acid have a high acidstrength, and the dehydration esterification can be performed simply byheating. Herein, it is attempted to perform the reaction in a toluenesolvent at 140-150° C. Finally, the temperature is raised to 160° C.,and an equimolar reaction is performed. Simultaneously however, half ofthe terminal alcohol is gradually added, when the majority of the acidis allowed to react except a terminal acid, the remaining alcohol isthen added and reacted. When 90-95% of the acid has been reacted,approximately 2.5 millimoles of an alkoxytitanium per 1 mole of acid isintroduced into the diol component, a mixture of 1 g ethylene glycol and0.5-1 g water is added, the activated catalyst is added, and thereaction is continued. It has already been stated that inactivation ofthe activated catalyst was found when using the diol component insteadof ethylene glycol, but the extent of the effect differs depending onthe type. If the reaction takes place smoothly, the reaction rate willdiffer depending on the reaction temperature, but the half-life of theacid can be arranged to be about 15-30 minutes, and the time at whichthe final acid value is obtained can be estimated. When the excessalcohol amount is small, the reaction is of course slower, so an excessdiol catalyst liquid prepared in the same way may be added in portionsas the reaction proceeds.

In this reaction, it may be expected that the acid diol reaction productreacts with acid to give AXA, but if an AXAX reaction takes place at thesame time, some A will remain in excess. Strictly speaking, the latterreaction cannot be prevented 100%, but the target can be achieved byperforming the reaction under mild conditions, and adding themonofunctional alcohol R in small amounts at a time. Excess diol mayalso react with the remaining A, but it probably first reacts with theproduct, forming an ester alcohol, and twice the number of moles of themonofunctional alcohol as the excess amount of diol are then produced ina transesterification reaction.

Regarding the effect of the excess used, the case will be consideredwhere it is used in the final stage of the reaction due to differencesof reaction type. Assuming that, in a reaction between 2 moles ofterminal alcohol (R), 2 moles of dibasic acid (A) and 1 mole of diol(X), 0.1 mole of X_(E), which is an excess of 10%, reacts:A+X→AX→partial addition reaction of R {RAX+A, RA}→RAXA+R+0.1X_(E)esterification→0.9RAXA+0.1RAX+0.1RAX_(E)→transesterificationreaction→0.7RAXAR+0.2RAXAXAR (i.e., R(AX)_(1.22)AR)

If 10% of the acid is RAR produced as a side product, n is1.22×1.25=1.53. Therefore, there is a problem in the reaction of theexcess amount. Specifically, if the object is (RAXAR+RAXAXAR) orRAXAXAR, and an excess of X is used relative to A, the reaction proceedswith a correspondingly lesser amount of R. By using the lesser amount ofR as the excess amount, the reaction may be made to proceed at the rateof the corresponding first-order reaction.

Manufacture of Hetero Complex Ester

When phthalic acid is used in the complex ester instead of adipic acid,a phthalate-phthalate (—PXPX—) structure is produced, and it is knownthat the viscosity of the product increases sharply. According to thisinvention, a method is proposed of quantitatively reacting thecorresponding components. By using an activated catalyst, when thealcohol is insufficient, the reaction rate become slower, and it may beverified whether the reaction is proceeding quantitatively by verifyingthe rate. To carry out the reaction quantitatively, an esterificationmethod is adopted wherein an excess is obtained by going through anester alcohol as an intermediate. An identical method is adopted forphthalic acid, but the aforesaid phthalate-phthalate structure could notbe eliminated. However, if a phthalate-adipate structure is adopted, usemay be made of the smaller rise in viscosity. If the target reaction is(RPXAR+RPXAR+RPXAXAR+RPXAXPRR), there are 6 moles of X (diol) and 8moles of R (terminal alcohol) for 5 moles of P (phthalic acid) and 5moles of A (adipic acid), and for 1 mole of A, X is 1.2 and R is 1.6. In(5RPXAR), there are 1 mole of X and 2 moles of R for 1 mole of A.However, the reaction starts with 0.2 more X and 0.4 less R, and ifadditions are made so that finally, R is 2, an alcohol amount of 0.4will be in excess. Esterification is performed, and after all the acidhas been converted to ester, transesterification is performed. Thereby,0.4 R corresponding to the excess is removed, and the product isobtained.

If the whole composition had the structure(RPXAR+RPXAR+RPXAXAR+RPXAXPR), RAR and RPR would not be produced as sideproducts. However, as the reaction rate of phthalic acid is slow andadipic acid reacts first at low temperature, a mixture is producedcontaining mainly RPR as a side product. According to this method, asdescribed above, adipate-phthalate is the main product, so its viscosityis relatively low at about 500 centipoise. From the viewpoint of thecomplex ester plasticizer test results of the prior art, expressing theplasticizer efficiency when used as a plasticizer for polyvinyl chloridein terms of the plasticizer amount which has an identical hardness tothat of 50 parts of dioctyl phthalate, DOP, this value is estimated as51-52. The target structure (RPXAR+RPXAR+RPXAXAR+RPXAXPR) is not limitedto this combination.

If the structure has a high polymerization degree as in RPXAXAXPR, theRPR produced as a side product decreases, but if a large amount ofphthalic acid is present, the viscosity rises. If the polymerizationdegree increases further, the viscosity increases and plasticizerefficiency is impaired.

Due to the use of this improved catalyst, a three component, and in thecase of a hetero complex ester, four component quantitative reaction wasobserved. If any catalyst is used, this feature is not evident, and thefact that a quantitative reaction can be performed is important. Hencepolyesters, complex esters and hetero complex esters which not only havea low alcohol termination with a low acid value, but also a narrowmolecular weight distribution, can be manufactured. In the Examples, itis noted that the lower the molecular weight of the diol, the morevolatile it is and the more easily it boils off together with water,which makes control difficult. These results are recorded in theExamples, but it should be understood that the invention is not limitedby the type of diol component.

Hereafter, this invention will be described by means of specificexamples, but it is not to be construed as being limited in any waythereby.

EXAMPLE 1 (Dehydration Esterification Reaction of Adipic Acid orPhthalic Acid)

0.65 g (36 millimoles) of water is added to and mixed with 1.49 g (24millimoles) ethylene glycol, and 0.41 g (1.2 millimoles)tetrabutoxytitanium is added in small amounts at a time to give agel-like mixture containing water.

10 g octanol is added to this gel-like polyolpolytitanic acid catalyst,stirred in and dispersed. The polyol-water activated titanium catalystis then reacted at 200-205° C. using 1.2 millimoles to one mol of adipicacid. The acid value of the reaction liquid was measured. Thetime-related change of the acid molar amount computed from the acidvalue is shown in FIG. 1. This reaction is a first-order reaction of anacid, and was the same as in the case of the polyol polytitanatepolytitanic acid of the above-mentioned patent, but its activity wasremarkably improved, the rate did not change until the last stage, theacid concentration decreased, and the half-life was 11 minutes.

Likewise, the above-mentioned polyol-water activated titanium catalystwas reacted at 190-195° C. using 1.5 millimoles to 0.5 mols of phthalicacid. The acid value of the reaction liquid was measured. Thetime-related change of the acid molar amount computed from the acidvalue is shown in FIG. 1. The reaction was a first-order reaction, andthe half-life was 13 minutes.

EXAMPLE 2

200 g of diester with an acid value of 0.6 was used for atransesterification reaction, which contains mainly dioctyl adipate, asmall amount of dioctyl phthalate removed as pre-distillate on producinga complex ester, and acid produced by thermal decomposition. To this, 30g of octanol was prevoiously added, followed by 1.2 millimoles of anethylene glycol-water activated titanium catalyst for thetransesterification reaction, and the mixture was heated with stirringat 200° C. for 1 hour. After 30 minutes, the acid value fell to 0.2, andafter 1 hour, the acid value was 0.1 or less, i.e., effectively zero.The pressure was reduced, octanol was removed and thetransesterification reaction was started.

EXAMPLE 3 Manufacture of Complex Ester-Polyester (Reaction Molar Ratioof Diol Diester and Diester=2:3)

0.5 moles (73 g) of adipic acid and one mole (134 g) of dipropyleneglycol were placed in a dehydration esterification reactor, and anazeotropic dehydration esterification reaction was performed with asmall amount of toluene. After 1 hour, 1.8 millimoles of the ethyleneglycol-water activated titanium catalyst of Example 1 was added, thereaction was continued, and one hour after the addition, the acid valuewas 0.14. After a further 30 minutes, the reaction was terminated,toluene was removed, the reaction mixture was transferred to anotherreactor, and a transesterification performed. Specifically, 0.75 moles(277.5 g) dioctyl adipate (DOA) prepared beforehand was placed under areduced pressure of 25 mm Hg at the water pump, a diol diester wasadded, and after 1 hour, an effectively stoichiometric amount of octanolwas recovered.

4 ml of cooling water was added to the reaction liquid, stirred, asolvent was added, and the reaction mixture allowed to stand. Activatedclay was then added, the filtrate was concentrated and distilled, and 56g DOA with 282.4 g of distillation liquid residue were thereby obtained.The proportion of the number of moles obtained by subtracting the numberof moles of DOA from the stoichiometric number of moles, by assuming thedifference from the computational amount of 336.5 as the number of molesof DOA, was calculated. Taking the inverse of this and assuming that thepolymerization degree has increased, the polymerization degree was 9.6,and the molecular weight of the polyester produced was 2712.

EXAMPLE 4 (Reaction Between Diol Diester and Diester in Reaction MolarRatio of 1:2)

0.6 moles (80.8 g) of dipropylene glycol was introduced into 0.2 moles(29.2 g) of adipic acid and 0.1 moles (14.8 g) of phthalic anhydride,and a dehydration esterification reaction was started with a smallamount of toluene. After 1 hour, 1.2 millimole of an active titaniumcatalyst was added. Three hours after the addition, the acid value(ml/g) was 0.11, and after a further 30 minutes, the reaction wascomplete. In another reactor, 1.5 moles of octanol was added to0.6-moles adipic acid, and a dehydration esterification was started.After 30 minutes, 1.1 millimoles of an active titanium catalyst wasadded, and the reaction was carried out at 180-200° C. After 1.5 hours,the acid value was 0.03 ml/g. Octanol was removed under reducedpressure, and the aforesaid diol diester reaction liquid was added underreduced pressure at the water pump at 200° C. The octanol produced after1.5 hours under 0.5 mm Hg at the vacuum pump was 79 g, corresponding tothe approximate calculation amount.

After cooling, 4 ml of water was added, the reaction was stirred at 80°C. for 2 hours, activated clay filtration was performed, and thefiltrate was concentrated and distilled under reduced pressure to give52 g of a DOA fraction and 200.9 g of the product. Considering thedifference from 259.4 g as DOA, the relative proportion of the number ofmoles from which this number of moles has been subtracted and thestoichiometric number of moles was calculated. From the inverse, thepolymerization degree was 2.11 times, and the molecular composition wasO(AX_(DP))_(3.52)(PX_(DP)) _(0.7)AO, molecular weight 1414. It isdetermined that the complex ester of this composition has excellentwater resistance and heating loss. In an example given in JapanesePatent Application Public Disclosure No. Hei 8-157418, results ofexperiments are shown for chemical amount:stoichiometry=1:2 Thecomposition of the product is shown when desorption of phthalic acidremoval (side product of DOP) due to the retroreaction and of diolcomponents is suppressed to the minimum by the use of a diol diester.2.11 times means that even if the reaction is performed for the purposeof n=1, the product has n=2.11. An extreme example of this is that aproduct of polymerization degree 2 containing 10% of polymerizationdegree 3 is possible. In practice, n=1 is ample, and as n progressivelyincreases, the molecular weight distribution should become smaller.

EXAMPLE 5 (Hetero Complex Ester, Diol Diester:Diester=1:2.5)

608 g propylene glycol was added to 0.66 moles (98.7 g) of phthalicanhydride, and heated and stirred. After reacting the anhydride, 1.33moles (194.7 g) of adipic acid were added, the mixture heated andstirred, and a reaction performed while removing the water produced.After about 1 hour, 1.8 millimoles of an ethylene glycol-water activatedtitanium catalyst was added. After 2 hours, the acid value was 0.07.

Propanediol was removed under reduced pressure, and 527.2 g diol diesterwas obtained as the remaining liquid.

For the formula:76/(527.2/2−192.7)=1,072HO(X_(p)A)_(0.66*1.072)(X_(p)P)_(0.3*1.072)XOHthe molecular weight is calculated to be 282.5.

A dehydration esterification reaction was performed by heating andstirring 146 g of adipic acid and 300 g of 2-ethylhexanol, and removingthe water produced. At 1.5 hours after starting the reaction, an octanolsuspension of 1.5 millimoles of an ethylene glycol-water activatedtitanium catalyst was added, and after 1.5 hours, the acid value was0.04 and the reaction was terminated. After distilling off and removingexcess octanol from the reaction liquid, the pressure was reduced to 70mm Hg, the reaction liquid was maintained at 210 or 180° C. underreduced pressure at the water pump, and 0.4 moles (113 g) of theaforesaid diol diester of molecular weight 282.5 was dripped into 1 moleof diester. Octanol was produced during the addition, removed bydistillation, and when the approximate stoichiometric amount had beendistilled off, the transesterification reaction was terminated. Aftercooling, 4 ml of water was added at about 100° C., the mixture wasstirred and left overnight, and hydrolysis of the catalyst wasterminated. Toluene dilution was performed, activated clay was added,and the mixture filtered. Next, the filtrate was concentrated, anddistilled under reduced pressure at 0.5 mm Hg to obtain 160.2 g ofdioctyl adipate as a side product. 218.8 g hetero complex ester wasobtained as the liquid residue. The calculated value of thestoichiometric amount, 305 g−218.8=86/2, 86/2/370=0.233. The number ofmoles obtained from the reaction was 0.4−0.233=0.167.

The polymerization rate of the product is the inversen=1/(0.167/0.4)=2.39. The molecular composition of the product wasO(AX_(p))_(4.11)(PX_(p))_(0.86)AO, and the molecular weight wascalculated to be 1312. In comparison with Example 24 of Japanese PatentApplication Public Disclosure No. Hei 8-157418, it appears that inaddition to water resistance, migration properties are sufficientlymaintained.

EXAMPLE 6 (Reaction of Hetero Complex Ester, Molar Ratio=1:2.85)

A mixture of 1.79 moles (260 g) of adipic acid and 500 g octanol wasplaced in a dehydration esterification reactor, heated, and the waterproduced was removed. After 1 hour, 1.5 millimoles of an activatedtitanium catalyst was used, and 3 hours after the reaction was started,the acid value was 0.08. 40 g of the diester obtained in theabove-mentioned Example 2 was added, and after adjusting to 1.9 moles ofliquid, 0.666 moles (188 g) of the diol diester having a molecularweight of 282.5 obtained in Example 4 was added at 210-180° C./70-25mmHg, and an octanol removal transesterification was performed.Post-treatment was performed as before. The catalyst was hydrolyzed, themixture filtered, the solvent removed by distillation, and 349.8 g ofproduct was obtained with 156 g of diester as a liquid residue. The samecalculation as before was performed, giving n=2.685 and a productcomposition of O(AX_(p))_(4.61)(PX_(p))_(0.96)AO, molecular weight 1425.From this composition, propanediol was probably produced together withoctanol in the transesterification reaction, but this could not beconfirmed.

The distillation is performed at high temperature, and if a long timeelapses, phthalic anhydride deposits in the distillation tube due topyrolysis. Heat resistance extends to a maximum of 250° C., so in orderto recycle DOA, the distillation must be performed below thistemperature.

EXAMPLE 7 (Reaction Molar Ratio of Diol Diester and Diester=1:4)

A mixture of 4 moles (536 g) dipropylene glycol and 0.267 moles (39.5 g)phthalic anhydride was pyrolyzed, and the anhydride was reacted. 0.533mols (78 g) adipic acid was added, heating dehydration was performed,and after 1 hour, a titanium catalyst was added to give an acid value of0.08. Dipropylene glycol was removed under reduced pressure at 120° C.,and 280.1 g of a liquid residue was obtained. A further 27 g ofdipropylene glycol was added, and taken to have a molecular weight of385. The aforesaid diol diester was added to 300 g DOA under reducedpressure, and a transesterification reaction was performed. The productof a 0.2 molar addition (molar ratio 1:4) was 162.5 g, and theside-product DOA which is recycled in this invention was 144.8 g. Theproduct composition was O(AX_(DP))_(1.94) (PX_(DP))_(0.39)AO, and themolecular weight was calculated to be 946. The viscosity was 326centipoises. The water resistance, measured by immersing a sheet in warmwater at 60° C. and measuring the % loss, was 0.91 compared to a valueof 0.8 for DOP. The loss on heating at 180° C. was 2.61 compared to 17%for DOP, and the softening temperature was −19.5° C.

EXAMPLE 8 (Diol Diester:Diester=3.37:1)

Following Example 7, 0.24 moles (92.3 g) was added to 300 g DOA, and atransesterification performed. The product yield was 182.0 g, and theamount of DOA which had to be recovered and recycled in this inventionwas 127.0 g. The composition was O(AX_(DP))2.33(PX_(DP))0.47AO, and themolecular weight was calculated to be 1062. Its viscosity was 334centipoise, water resistance was 0.89, loss on heating at 180° C. for 2hours was 2.03, and softening temperature was −19.0° C.

EXAMPLE 9 (Reaction Molar Ratio of Diol Diester and Diester=1:2.89)

Following Example 7, the reaction molar ratio was varied, 0.28 moles(92.3 g) diol diester was added to 300 g DOA, and a transesterificationwas performed. The product was 206.9 g, and the DOA to be recovered andrecycled was 97.5 g. The product composition wasO(AX_(DP))_(2.52)(PX_(DP))_(0.551)AO, and the molecular weight wascalculated to be 1119. The viscosity was 393 centipoise. Theplasticizing efficiency when used as a plasticizer was 51, approximatelyequivalent to that of dioctyl phthalate, DOP. The waterproofing testgave 0.69, heat loss at 160° C. was 2.65, which was much less, and thesoftening temperature was −16.5° C.

Examples 7-9 are examples given in Japanese Patent Application PublicDisclosure No. Hei 8-157418 by the Inventor. Regarding the amount to berecycled required by this invention and the plasticity obtained, clearresults are given, but the previous method of performing the compositioncalculation has been corrected to give the molecular weight. Theplasticity of the complex ester disclosed in these Examples 7-9 is verygood. This shows excellent anti-volatility characteristics, but thegeneration of a large amount of DOA as a side product is a problem.

EXAMPLE 10 (Reaction of Ester Alcohol and Diester)

A dehydration esterification reaction was started using a mixture of 0.5moles of adipic acid, 0.25 moles of 2-ethyl 1,3 hexane diol and 0.75moles of octanol. After 1 hour, 1.7 millimoles of an activated titaniumcatalyst was added. 30 minutes later, the acid value was 1.66, one hourlater it was 0.49, 1.5 hours later it was 0.05, and 30 minutes later thereaction was terminated. After the reaction was complete, the degree ofpressure reduction in the reactor was gradually increased. Finally, thepressure was reduced by the water pump, the temperature was maintainedat 200-210° C. for 1.5 hours, the pressure was maintained at 0.5 mm Hgfor 30 minutes, and the octanol produced was removed. After the reactionwas complete, water was added, the temperature increased, stirringperformed for 3 hours, the mixture filtered to remove titanium residues,and evaporated under reduced pressure. 55.1 g of a DOA fraction and102.7 g of the product were obtained. The composition wasO(AX_(2E))_(2.41)AO, and the molecular weight was calculated to be 987.The performance when this was used as plasticizer is described foresters manufactured to obtain polymerization degrees of 1.5 and 2.5 inJapanese Patent Application Public Disclosure No. Hei 6-172261. Inaddition to plasticizer properties, due to the effect of the side chainat the 1,3 position of the diol component, the ester group is not easilyattacked, and water resistance properties are excellent. As thisexcellent ester is a homopolymer, the viscosity and molecular weightdistribution are close to those of a normal distribution, and it is alsosuitable for use as a plasticizer. In this reaction, alcohol is used inexcess, so there is no problem when the acid value is lowered. When thecatalyst is used to perform esterification in one step, various complexesters can be manufactured in a very short time provided that the molarratio is maintained. Only removal and recycling of the diester which isused in excess is a problem. According to this invention, an amountwhich takes account of diester side production is used as the excess,and the DOA produced as a side product in the aforesaid reaction isadded and recycled with a view to re-use in the transesterification.

EXAMPLE 11

A mixture of 1.2 moles (175.2 g) adipic acid, 0.6 moles (80.4 g)dipropylene glycol and 1.8 moles (234 g) octanol were placed underreduced pressure, the atmosphere replaced by nitrogen, and a dehydrationesterification reaction started. After 1.5 hours at 180-200° C., when90% of the water had been removed by distillation, an octanol suspensionof 2 millimoles of an ethylene glycol-water activated titanium catalystwhich had been prepared separately, was added. 1.5 hours after theaddition, the acid value (ml/g) was 0.08, and after a further 30minutes, the reaction was terminated. 0.6 moles (222 g) of dioctyladipate, DOA, which had been prepared for recycling to the reactionliquid, was added, the temperature was lowered, the system was changedover to reduced pressure, and then the temperature was raised and heldat 200° C. under a reduced pressure of 25 mm Hg at the water pump.During this process, octanol began to distil off, and after 1 hour, adiol diester solution, prepared separately, was added and thetransesterification reaction continued. The diol diester solution wasprepared by placing a mixture of 0.3 moles of phthalic anhydride and 0.6moles (80.4 g) of dipropylene glycol in a nitrogen atmosphere, adding asmall amount of toluene, and performing a dehydration esterificationreaction at a temperature in the vicinity of 200-210° C. At the end ofthe reaction, 0.8 millimoles of an ethylene glycol-water activatedtitanium catalyst was added. 1.5 hours after the addition, the acidvalue was reduced to less than 0.1, and 30 minutes later, the productwas used as an addition liquid. In the addition esterification reaction,if the addition is rapid, octanol distils off early, but the additionwas made small amounts at a time while observing the amount of octanolreleased. The addition was complete after about one hour. Finally, thereduced pressure in the reactor was raised to 0.5 mm Hg, and all theoctanol was removed together with part of the DOA. The octanol removedwas approximately the stoichiometric amount, i.e., 152 g including thesmall amount of DOA. When the reaction liquid reached 100° C., 200 ml oftoluene diluent and 6 ml of water were added, and the reaction mixturewas left while stirring was continued. Next, activated clay filtration,concentration and reduced pressure concentration distillation wereperformed, fractions at 0.5 mm Hg up to a temperature of 250° C. werecombined with the fraction from the previous transesterification, and205 g of DOA were recovered. 465 g of the target complex ester,stoichiometric formula O(AX_(DP))₂(PX_(DP))_(0.66)AO, was obtained as aliquid residue, and the corresponding product was 408.4 g. Thecomposition of the product was O(AX_(DP))_(3.03)(PX_(DP))_(1.00)AO, andthe molecular weight was calculated to be 1373.

EXAMPLE 12 (Ester Alcohol-Diester Reaction/Molar Ratio RPXOH:R′AR′=1:2)

In Examples 12-18, the following symbols are used: A: adipic acid, P:phthalic acid, R: terminal alcohol (2 ethylhexanol), R′: terminalalcohol (1-octanol), X_(DP): dipropylene glycol used as diol component,X_(13B): 1,3-butanediol used as diol component. The polymerizationdegree is indicated by ( ) with a subscript.

The diols and terminal alcohols are not limited to those in theExamples. The same reasoning can be applied to the diols and terminalalcohols (C₄-C₁₀ used and considered in the prior art.

The ethylene glycol-water activated titanium catalyst used in Examples12-18 was prepared as follows. 0.65 g (36 millimoles) of water was addedto ethylene glycol 1.49 g (24 millimoles) and mixed, 0.41 g (1.2millimoles) of tetrabutoxytitanium was added in small amounts at a time,and a gel-like mixture containing water was formed. 10 g octanol wasadded to this gel-like polyol polytitanic acid, stirred and dispersed,and a polyol-water activated titanium catalyst was thereby obtained.

A mixture of 0.33 moles (49.6 g) of phthalic anhydride and 0.33 moles(44.7 g) of dipropylene glycol was stirred, and an anhydride reactionperformed. 1.5 millimoles of the ethylene glycol-water activatedtitanium catalyst was then suspended in 0.33 moles (43.3 g) of2-ethylhexanol, added to the reaction liquid, and a dehydrationesterification performed. 1.5 hours after the addition, the acid valuewas 0.1, the reaction was continued for 30 minutes, and terminated. Thereaction liquid was divided into two parts, and 66.4 g of this reactionproduct (0.166 moles for each mole of reaction product, RPXOH) was thenadded to the reaction liquid containing 0.34 moles (125.5 g) of dioctyladipate (R′AR′) and 0.8 millimoles of titanium catalyst under a reducedpressure of 5-1 mm Hg.

Corresponding to the addition, octanol containing toluene was distilledoff, and 29.7 g was recovered. The addition transesterification wasterminated, and when the temperature had fallen to 100° C., 5 ml ofwater was added, and the mixture stirred. After 2 hours, toluene wasadded and filtered by using active clay, and activated clay filtrationwas performed. The filtrate was distilled to remove solvent, volatileconstituents (corresponding to R′AR′, etc.) were removed at 190-250°C./0.5 mm Hg, and 73.6 g of product was obtained as the liquid residue.

32.1 g, the difference from the theoretical value of 105.7 g, iscalculated to be 0.087 moles (mw=370) of dioctyl adipate, the proportionof the number of moles reacted, 0.08, is 0.477, and the inverse, 2.05,is the polymerization rate. As a result, the product is R(PX)_(2.05)AR′,molecular weight 911.2. The viscosity at 20° C. was 868 centipoise.

EXAMPLE 13 (Reaction Molar Ratio RPXOH:R′AR′=1:2.5)

A small amount of octanol was added to 160.2 g dioctyl adipate recoveredin the reaction of 65.7 g (0.167 moles) of RPXOH ester mixed liquidobtained in the first step of Example 2, and stirred with an activetitanium catalyst at 200° C. for 1 hour to make the acid value 0.06.Octanol was removed under reduced pressure, and addition performed withstirring at 5-0.5 mmHg. A transesterification reaction was performed for1 hour, and after 30 minutes, post-treatment was performed as before,distillation was performed at 190-250° C./0.5 mm Hg, dioctyl adipate wasremoved as the pre-distillate, and the product was obtained as theliquid residue. The weight was 78.5 g, reaction molar number was 0.0935,proportion was 0.559, inverse n was 1.79, and viscosity at 20° C. was664 centipoise.

EXAMPLE 14 (RPXOH:R′AR′=1:2.75)

0.33 moles (49.0 g) of phthalic anhydride and 0.33 moles (44.2 g) ofdipropylene glycol were heated and stirred, 43.3 g (0.333 moles) of2-ethylhexanol in which 1.2 millimoles of an ethylene glycol-wateractivated titanium catalyst was suspended, was added, and a dehydrationesterification reaction was performed. After 2.5 hours, the acid valuewas 0.08, and after a further 20 minutes, the reaction was terminated.

A mixture of 200 g recovered dioctyl adipate and 76 g fresh dioctyladipate was placed under reduced pressure. After heating to removesufficient volatile constituents, the dehydration esterificationreaction product was added over 1.5 hours at 190° C./0.5 mmHg withstirring, 42 g of the octanol produced was removed and the reaction wasterminated. Water was added at 100° C., the catalyst was inactivated,and active clay filtration was performed. The filtrate was concentrated,distilled at 190-250° C./0.5 mm Hg, and 197 g dioctyl adipate wasremoved as a volatile constitutent to obtain 157.9 g as the remainingliquid. The reaction molar number was calculated taking the differencefrom the stoichiometric amount of 209.5 g as diester. The inverse of itsproportion, 0.576, gave a polymerization degree of 1.736. From this, thecomposition of the product was R(PX_(DP))_(1.74)AR′, and its molecularweight was calculated to be 829. The viscosity at 20° C. was 464centipoises, estimated as RPXA(XP)_(0.74)R′, and it is thought that theviscosity was lower as it did not contain (PX)₂. Looking at the productwhen the reaction molar ratio was varied in the sequence 2, 2.5, 2.75,the polymerization degree falls in the sequence 2.05, 1.79, 1.74, andthe viscosity gradually decreases accordingly, but when thepolymerization degree exceeds 2, the viscosity rises sharply. When theviscosity increases, the plasticizing efficiency when it is used as aplasticizer for polyvinyl chloride correspondingly worsens, so in orderto obtain outstanding plasticity, the reaction molar ratio is 2.5-2.75.

It is well known that water resistance and weatherability improve, thelarger the number of phthalic acid units.

EXAMPLE 15

2 millimoles of an ethylene glycol-water activated titanium catalyst wasadded to a mixture of 0.7 moles (102.2 g) adipic acid, 0.7 moles (63 g)of 1,3 butanediol and 0.7 moles (91 g) of 1-octanol. After replacing airwith nitrogen, the mixture was heated, and a dehydration esterificationreaction was performed in the presence of a small amount of toluene.After 2 hours 15 minutes, the acid value was 0.10, and after a further30 minutes, the esterification reaction was terminated. The product wasconcentrated under reduced pressure, toluene and 1-octanol were removed,and a yield of 214.2 g was obtained.

The amount, which is 16.8 g less than the calculation amount, wasdivided by 130 as octanol, and the analysis usage amount was correctedby 1.8 g, this gave a reaction molar amount of 0.585 moles, and aproportion of 0.837. The polymerization degree was 1.196, thecomposition was R(AX_(13B))_(1.196)OH and the molecular weight was369.3. 103 g, 0.278 moles of dioctyl adipate was heated, and maintainedat 180° C./0.5 mm Hg with stirring, 0.58 moles, 214 g (0.58/0.278=2.08times moles) of the aforesaid ester alcohol was added, and atransesterification was performed. The stoichiometric composition wasR(AX_(13B))_(2.08)AR′, 74 g octanol was recovered from 0.278 moles,218.6 g, and combined with the aforesaid amount to give theapproximately quantitative amount. Post-treatment was performed asbefore, distillation was carried out under reduced pressure at 190-250°C./0.5 mm Hg to remove volatile constituents, and 195.6 g product wasobtained as the residual product. The insufficient amount of 23 g wasdivided by the molecular weight of the diester, giving 0.062. Thereaction molar number was 0.215, and its proportion was 0.776. Thepolymerization degree was the inverse, 1.28. The composition wasR(AX_(13B))_(2.68)AR′, molecular weight 905.8. The viscosity at 20° C.was 224 centipoise.

EXAMPLE 16

2 millimoles of ethylene glycol-water activated titanium catalyst wasadded, together with a small amount of toluene, to 0.4 moles (58.4 g)adipic acid, 0.4 moles (36 g) of 1,3 butanediol and 0.4 moles (52 g) of1-octanol, and a dehydration esterification reaction was performed.After 2.5 hours at 200° C., the acid value was 0.08. Toluene was removedunder reduced pressure, and 130 g of the reaction liquid was used forthe next reaction. A dehydration esterification was started with amixture of 4 molar equivalents of adipic acid and 3 molar equivalents of1,3-butanediol manufactured separately, and 2 molar equivalents of1-octanol was added to perform the dehydration esterification to give toR(AX_(13B))_(4.57)AR′, molecular weight 1264. The viscosity at 20° C.was, 588 centipoise. 0.8 millimoles of tetrabutoxytitanium was added to0.035 moles (44.2 g) of the latter compound, 130 g of the aforesaidester alcohol was added in small amounts at a time over 1.5 hours at180° C./0.5 mm Hg with stirring, a transesterification reaction wasperformed, and 50 g of the octanol produced was recovered. The filtratefrom clay filtration for rendering the catalyst inactive wasconcentrated and distilled under reduced pressure by the standardmethod, volatile constituents were removed, and 122.0 g of product wasobtained as the liquid residue. The volatile material did not containfractions which boiled even at 250° C./0.5 mm Hg, so either the esterhad reacted and disappeared, or it was not present. As 0.4/0.035=11.42times the amount of RAXOH was made to react, the polymerization degreewas 4.57+11.42=15.98, and the composition of the product wasR(AX_(13B))₁₆AR′, molecular weight 3570. The viscosity at 20° C. was1952 centipoise.

EXAMPLE 17

0.5 moles (58.5 g) of 2-ethylhexanol and 2.5 millimoles of an activatedtitanium catalyst were added together to a mixture of 0.3 moles (43.8 g)adipic acid and 0.15 moles (20.1 g) of dipropylene glycol, and adehydration esterification reaction was performed. The product was amixture of 0.15 moles each of RAXOH and R′AR′. R(AX_(DP))_(1.2)OH andR(PX_(DP))OH were also manufactured for a different purpose. 2millimoles of the activated titanium catalyst was added to 0.5 moles ofadipic acid, 0.5 moles of dipropylene glycol and 0.5 moles of2-ethylhexanol, a small amount of toluene was added, a dehydrationesterification reaction was performed at 200-210° C., and the acid valuewas lowered. Next, volatile octanol was removed under reduced pressureat 25 mm Hg, 100° C. or lower to obtain 176.2 g of product. Thepolymerization degree obtained by calculation was 1.20, the molecularweight was 422.8, and 0.3 moles thereof was used. R(PX_(DP))OH wasmanufactured by the following method. 0.1 moles (13.4 g) of dipropyleneglycol, 0.1 moles (13 g) of 2-ethylhexanol and 0.8 millimoles (0.3 g) oftetrabutoxytitanium were added to 0.1 moles (27.8 g) of dibutylphthalate. The butanol produced by heating and stirring the reactionmixture at 180° C., first at ordinary pressure and then at 200 mm Hg,was removed. Approximately the stoichiometric amount, 14 g, of butanolwas obtained, the reaction was terminated, and the product used for anaddition reaction.

First, the solution of RAXOH+R′AR′ was placed under reduced pressure,the temperature was raised with stirring, and the octanol produced wasremoved. The temperature was adjusted to 180° C., the reduced pressurewas adjusted to 15 mm Hg, 0.3 moles (126.8 g) R(AX_(DP))_(1.2)OH and 0.1moles (39 g) R(PX_(DP))OH were added, and a transesterification wasperformed. The octanol produced, approximately 70 g, was removed, andafter 2 hours, the reduced pressure was raised to 0.5 mm Hg, thetemperature was maintained for 30 minutes, and the reaction wasterminated. Post-treatment was performed according to the standardmethod, the solvent was removed, distillation was performed underreduced pressure, and volatile constituents were removed to give 195.5 gof product as the residual substance. For a product stoichiometric valueof R(AX_(DP))_(3.4)(AX_(DP))_(0.66)AR′, 206.3 g, n=1.24. The compositionof the product was therefore (AX_(DP))_(4.22)(PX_(DP))_(0.83)AR′,molecular weight 1619. The viscosity at 20° C. was 820 centipoise.

EXAMPLE 18 Example Use of Propanediol (RPXOH:R′AR′=1:2.7)

0.5 moles, 65 g of 2-ethylhexanol and 100 g of toluene were added to 0.5moles, 74 g of phthalic anhydride, the mixture was stirred at 85-95° C.for 4 hours, and the anhydride was reacted. Next, 1 gtetrabutoxytitanium was introduced and dissolved in 56 g of1,2-propanediol, i.e., 1.5 times the molar amount of 0.75 moles, an 0.8g ethylene glycol-0.8 g water mixture was added with stirring, and theactivated titanium catalyst was separated out to give a catalystsolution which was added to perform a dehydration esterificationreaction. Water containing propanediol which had distilled off wasreturned to the reactor, the azeotropic solvent toluene was removed, thetemperature was raised and the reaction was carried out to lower theacid value. After 4 hours, the remaining acid amount was 0.004 moles andthe reaction was terminated. The remaining solvent and propanediol wereremoved under reduced pressure to give 164 g of 12-propanediolphthalate, OcPX_(p)OH. The difference from the stoichiometric amount of168 g is due to the production of 12-propanediol phthalate,HOX_(p)PX_(p)OH, and the product contained a small amount of dioctylphthalate. Its viscosity at 20° C. was 660 centipoise. 500 g (1.35moles) of dioctyl phthalate (DOA) was added, the mixture was heated andstirred at 180-205° C., first under a slightly reduced pressure, nextunder the reduced pressure of the water pump and finally under 0.3 mmHg, and 60 g of octanol which was a product of the transesterificationreaction and had distilled off, was removed. The reaction mixture wascooled, a small amount of water and toluene were added at 100° C. andstirred, active clay was added to adsorb the titanium catalyst, andfiltered to remove the catalyst. The solvent was distilled off from thetoluene diluted solution, and finally, under 0.3 mm Hg, the temperaturewas raised to 260° C., 310 g of volatile constituents (DOA) was removed,and 234.4 g of product was obtained. The difference from thestoichiometric amount, 288 g, was 53.6 g DOA/370=0.145 moles, and themolar amount of the product was 0.355. Therefore, from(206n+370)×0.355=234.4, or from the inverse of the reaction amount permole, the polymerization degree n=1.41. The composition wasO(PX_(p))_(1.41)AO, Mw=661. The viscosity of the product at 20° C. was510 centipoise. In a comparison with viscosity, regarding plasticizerproperties when used as a plasticizer for polyphenol chloride, the usageamount showing an equivalent value to when 50 PHR of DOP was used, wasestimated to be 51-52. This is the same or slightly worse, butevaporation losses were almost negligible, and there was no worsening oflow-temperature properties. Hence, it is considered that the product canbe used as a plasticizer with excellent non-volatile properties. In thisexperiment, with esterification products for which the acid value doesnot decrease, the transesterification reaction does not proceedproperly. Moreover, when volatile constituents are removed, phthalicacid anhydride, which is a pyrolysis product, separates in thedistillation apparatus, and a water rinse-alkali rinse is required tolower the acid value. In this method, the production of phthalic aciddiesters is reduced to the absolute minimum, and there are no sideproducts due to the recycling of adipic acid esters. Therefore, aproduct of different polymerization degree m is produced depending onthe reaction proportion with adipic acid diesters, a sharp rise inviscosity due to phthalic acid is prevented, and excellent plasticizerproperties are obtained. Fractions in the polymerization degree indicatecompositions having a higher degree. According to this method,phthalate-phthalate is not produced and phthalate-adipate is mainlyobtained, so the viscosity of the product does not increase, and anexcellent product is obtained.

EXAMPLE 19 (Object: di-2-ethylhexylpoly(15)ethane diol adipate (n=15,Molecular Weight 3000)

A mixture of 5 moles or 730 g of adipic acid, and 300 g of ethyleneglycol, comprising 5×10/11 moles of ethylene glycol corresponding to amolecular weight of 2000, i.e., 281.8 g, and 18.2 g as a correctionamount corresponding to diol which distils off azeotropically withwater, were placed in a reaction vessel together with 100 g of toluene,the atmosphere was replaced by nitrogen, and a dehydrationesterification reaction was started. The reaction was carried out whilerecycling and returning water which had azeotropically distilled off at130-150° C. to the reaction vessel, and the water produced was removed.5×2/11 moles or 118.2 g of 2-ethylhexanol, a terminal alcohol,corresponding to a molecular weight of 2000, was divided into threeparts. Half was added from the beginning in small amounts at a time.After the water distilled off had exceeded half the amount, 100 g, thetemperature was gradually raised, 22.5 g was added, and when it hadexceeded 90%, the remaining 2-ethylhexanol, 379 g, was finally added.The temperature was lowered, 5 g tetrabutoxytitanium was dissolved inthe difference, 8.8 g, from the ethylene glycol amount, 5×15/16, 290.6g, corresponding to a molecular weight of 3000, a mixture of 2 gethylene glycol and 1.5 g water was added with stirring, and theactivated titanium was separated out. This activated catalyst suspensionwas added, and a dehydration esterification performed. While maintainingthe reaction temperature at 200° C., esterification was carried out. Therate of the first-order reaction calculated from the logarithm of theremaining acid amount deduced from the final acid value and the time,gave a half-life of approximately 20 minutes. The remaining acid amountwas 0.002, and after 30 minutes, the reaction was terminated.

Next, a distillation tube was attached, the reduced pressure wasincreased to 0.3 mm Hg, and the octanol which distilled off was removed.The transesterification reaction liquid was cooled, toluene and 1 g ofwater were added, and stirred. 40 g of activated clay was added, themixture allowed to stand, the catalyst sedimented by adsorption, andfiltered off from the supernatant liquid. Next, toluene was distilledoff to give 920 g of a product [P]. The polymerization degree n wascalculated as {[P]−370×51/{5×172·[P]}. As n=15 corresponds to amolecular weight of 2950, the product had n=15.5 and the molecularweight was 3036. Thus, a polyester having a number average molecularweight of 3140 as determined by GPC, a weight average molecular weightof 6020, and an excellent distribution with a dispersion of 1.917, couldbe manufactured to a target molecular weight of 3000.

This polyethylene adipate is a polyester having a low acid value andcontaining almost no terminal alcohol. It has excellent miscibility willpolyethylene terephthalate resin, and in an extrusion test using a 10inch kneading machine, up to 8% could be added and mixed in. It wasfound that at 10%, dissolution was incomplete, and the substance flowedback to collect in the feed part. With other plasticizers, even2-ethylhexyl phthalate and other complex esters, no ester was foundwhich could be introduced in more than 3 parts. In a block polyesterwith polyethylene terephthalate prepared from polyethylene adipate ofmolecular weight 3000, up to 45 parts can be introduced under theaforesaid conditions, and it was found that in admixture therewith, the8 parts could be increased to 15 parts.

EXAMPLE 20 (Object: di-2-ethylhexylpoly(6)1,3-propane diol adipate (n=6,Molecular Weight 1486)

80 g toluene was added to a mixture of 3 moles, or 438 g, of adipicacid, and 3×4/5 moles, or 182 g, of 12-propanediol as an amountcorresponding to a molecular weight of 1114 with 35 g excess as theazeotropic distillation fraction with water, the atmosphere was replacedby nitrogen, and a dehydration esterification reaction was started.3×2/7 moles, or 111 g, of 2-ethylhexanol was added in small amounts at atime while removing water at 130-150° C., the water which distilled offtogether with the propanediol during this process was recycled andreturned to the reaction liquid, and the reaction was carried out untilhalf the stoichiometric amount of water, 60 g, had distilled off.Subsequently, the temperature was raised to 170° C., the reaction wascontinued, and finally, (2/5-2/7) molar equivalents, 40 g, of2-ethylhexanol was added. After 95% or more of the esterification hadtaken place, the temperature was lowered. 4 g of tetrabutoxytitanium wasdissolved in a propanediol amount different from the amountcorresponding to a molecular weight of 1500, 76×3×(6/7-4/5), or 13 g.The activated catalyst, which was obtained by adding a mixture of 1 gethylene glycol-1 g water, was added, esterification was carried out atapproximately 200° C., the acid value was lowered corresponding to thefirst-order reaction, and its half-life was approximately 25 minutes.

Next, the product was placed under reduced pressure, atransesterification reaction was carried out at 210° C./0.3 mm Hg, andoctanol, a volatile constituent, was removed. After the temperature hadfallen to 100° C., toluene and 1 g water were added with stirring. Theresulting activated catalyst was added, the separated titaniumsedimented by aggregation, and was filtered to remove the catalyst. Thesolvent was removed by distillation, giving 631.5 g of a product [P] asthe liquid residue. The polymerization degree n was calculated as{[P]−3×370}/{3×186−[P]}. For the polyester obtained, n=6.51, averagemolecular weight was 1581, and the effective average molecular weight byGPC analysis was 1600. The distribution was excellent with a dispersionof 1.98. The viscosity at 20° C. was 1440 centipoise. The error in thetarget molecular weight was related to the correction amount of theazeotropic fraction of propanediol. The excess amount due to azeotropicdistillation is an amount obtained by determining the correction amountexperimentally, and it should be modified depending on the recyclingamount and reaction temperature. In particular, with propanediol, thecorrection amount must be computed to suit the molecular weight.

Polyester plasticizers are used as plasticizers for polyvinyl chloride,and their low volatility is well known. However, compared to diesterplasticizers, they are high-cost and high viscosity, their plasticizerefficiency is poor and a large amount must be used. Due to thesedisadvantages, their range of applications was limited. Plasticizerpolyesters with a molecular weight of 2000-4000, having a resistance tomigration, are manufactured and marketed for use in conjunction withapproximately 1000 polyesters and other resins. The method of thisinvention is low-cost due to the use of highly activated catalysts, andpolyesters with no low molecular weight fraction and excellent molecularweight control can be selectively manufactured by transesterificationreactions. Further, by selecting the diol component, a polyester havingexcellent low-temperature properties and viscosity properties can bemanufactured.

EXAMPLE 21 (2-ethylhexyl 1,2-propanediol adipate)

The reaction molar ratio from the composition was adipic acid 2, diol 1and octanol 2, and the reaction was performed with a reactioncomposition of adipic acid 2, diol 1.25 and octanol 1.5(RAXAR+2RAXAXAR). Considering (2RAX+3RAXAR) as the intermediatecomposition, the usage amount of R is +2R, an esterification reactionwas performed with this additional amount, and the amount correspondingto 2R was removed in the transesterification reaction to obtain thetarget product. This example is shown below.

1 mole of 146 g adipic acid, 47.5 g of 12-propanediol and 7 g as anexcess amount were introduced into a reactor, a dehydrationesterification reaction was performed at 140-150° C., and esterificationwas carried out while returning the aqueous layer to the reactor torecover propanediol. 65 g of 2-ethylhexanol was added when the waterdistillation amount was approximately half of the stoichiometric amount,20 ml, the temperature was raised to 180-200° C., and the remaining 38 gwas then added to perform esterification. Finally, 38 g (total amount isequimolar amount relative to acid) of 2-ethylhexanol was added as anadditional amount. Subsequently, the temperature was lowered, 1.5 gtetrabutoxytitanium was dissolved in 10 ml toluene, and a mixture of 0.8g ethylene glycol-0.8 g water was added with stirring. The resultingactivated titanium catalyst was added, an esterification reaction wasperformed, and a reaction was performed with an approximate half-life of20 minutes.

Finally, with the system under reduced pressure at 200° C./0.3 mm Hg, atransesterification was performed to remove volatile constituents, andthe reaction was terminated. Toluene-water was added, active clay wasadded, the catalyst was filtered and the solvent was removed bydistillation. The temperature was raised to a maximum of 270° C. at areduced pressure of 0.3 mm Hg to remove DOA by distillation, and 201.5 gof a product [P] was obtained as the liquid residue. The viscosity at20° C. was 140 centipoise. The difference from the yield of 278 gcalculated from one mole of adipic acid with n=1 was 76.5/370=0.206 asthe number of moles of DOA. Further, using a value of 1−0.206=0.793 asthe number of moles which reacted as complex ester, n is calculated tobe {[P]−370×(1−0.206)}/{186×(1−0.206)−[P]}, so n=1.70. The excess ofpropanediol used is the amount that distils off as an azeotropiccomponent together with water found by experience from precedingexperiments. Theoretically, if the target composition is obtained,n=1.66, but it is extremely difficult to obtain a quantitative reactionexcluding the azeotropic fraction, and this is the first time that apolymerization degree of 1.70 has been obtained directly by this method.If a complex ester having a small n or other diols are used, n=1.4 isobtained by the direct method. This reaction is insufficient if thealcohol amount does not react quantitatively, or intermediate productsof ester alcohols remain, and the rate of the first-order reaction isremarkably slowed. Conversely, it can be determined from the reactionrate whether the reaction has proceeded quantitatively. From theviscosity of the product obtained, it was estimated that althoughplasticizer efficiency was 10% less when the ester was used as aplasticizer for polyvinyl chloride, it had excellent propertiesexhibiting an identical surface hardness. It had low-temperatureproperties, and is expected to be used as a plasticizer with very littlevolatility even when used for long periods.

EXAMPLE 22 Manufacture by Recycling Method Using Propanediol(2-ethylhexyl poly(1,7) 1,2 propanediol adipate)

The boiling point of 1,2 propanediol is low and it distils offazeotropically with water, so it is very difficult to perform thereaction quantitatively. An example will now be given where, assumingthat dioctyl adipate, DOA (may be abbreviated as RAR) is produced as aside product, this side product DOA is used. This is an example where,in the same way as a reaction is performed with recovered DOA using anester alcohol corresponding to RAX, a complex ester is manufactured byproducing RAX while partly producing DOA simultaneously, and reactingthis with recovered and recycled RAR.1.5 HOCOACOOH+HOXOH+2 C₈H₁₇OH→1 C₈H₁₇OCOACOOXOH+0.5 C₈H₁₇OCOACOOC₈H₁₇→+2C₈H₁₇OCOACOOC₈H₁₆→C₈H₁₇O(COACOOXO)_(1.70)COACOOC₈H₁₇+C₈H₁₇OCOACOOC₈H₁₇

1.5 moles, 219 g of adipic acid, 1 mole, 76 g of 1,2 propanediol, and 15g excess amount as the azeotropically distilling fraction, were placedin a reactor, the atmosphere was replaced by nitrogen, and the reactionwas started at

140-160° C. The reaction was carried out while recycling and returningwater which distilled off to the reactor, and half the amount ofoctanol, 1 mole, 130 g, was simultaneously added in small amounts at atime. Propanediol was sufficiently reacted, and after approximately halfthe stoichiometric amount of water had been discharged, the temperaturewas raised to 180-200° C., and the reaction was continued while adding90 g of octanol. Finally, the temperature was lowered, 3 gtetrabitoxytitanium was dissolved in 40 g octanol, and a mixture of 1 gethylene glycol-1 g water was added with stirring. The resultingactivated titanium suspension was added, and a dehydrationesterification reaction was performed.

The excess amount of alcohol corresponds to the molar amount of diol,and the reaction was carried out with a half-life of approximately 20minutes.

After the acid value was sufficiently lowered, the reaction mixture wasplaced in the recovered DOA, 740 g, placed under reduced pressure at atemperature of 180-200° C. with stirring, and the solvent and octanolproduced by transesterification were removed.

Finally, the pressure was lowered to 0.3 mm Hg to sufficiently removeoctanol, and the reaction was terminated. When the temperature hadfallen to 100° C., 400 ml toluene and 2 ml water were added withstirring, 40 g of active clay was added with stirring, and the mixtureallowed to stand to sediment the catalyst. Subsequently, the mixture wasfiltered, the solvent was distilled off, and finally DOA was removedunder reduced pressure at a maximum temperature of 270° C./0.3 mm Hg.Its amount was 674 g. The product was 406 g as the liquid residue, thedifference from the stoichiometric amount, 556 g, produced from one moleof reacted adipic acid, i.e., 150 g, was 405 moles of DOA, and theamount reacted with the complex ester of adipic acid was 2−0.405=1.595moles. From the following equation:(186n+370)×1.595/n+1=406, n=1.68. Therefore, the molecular weight was682.

This is an example where RAX is produced and reacted while partlyproducing RAR, which is recycled and consumed. RAX can also be producedas the object, in which case a target product corresponding to RAXAR ispartly produced simultaneously. In the transesterification reaction, theobtaining of a reaction liquid containing RAXAR is a difference, but ifthe excess of RAR does not undergo transesterification, a complex esterhaving a small value of n cannot be obtained. This is the same in thisexample, the value of n becoming smaller the larger the proportion ofRAR in the reaction.

EXAMPLE 23 di-2-ethylhexyl poly(1,4) 1,2 propaneoxy 1,2-propanedioladipate (dipropylene glycol bis-2-ethylhexyl adipate)

2 moles, 292.2 g of adipic acid, and 1.1 moles (0.1 moles excess), 147g, of dipropylene glycol were introduced into a dehydrationesterification reaction apparatus, and the atmosphere was replaced bynitrogen. The reaction was performed at 140-160° C., and 130 g of2-ethylhexanol was added in small amounts at a time up to 40 ml as waterdistilled off. The temperature was raised, the remaining 100 g wascontinuously added in small amounts at a time, and when more than 90%had been added, an activated titanium catalyst, produced by dissolving 3g tetrabutoxytitanium in 30 g of 2-ethylhexanol and adding a mixture of1 g ethylene glycol-1 g water with stirring, was added and the reactionwas performed at 200° C. The half-life of the first-order reaction was20 minutes.

After performing the transesterification reaction at 200° C., tolueneand water were added, and hydrolyzed. Active clay was added, and thecatalyst was separated by sedimentation filtration, and the filtrate wasconcentrated. Finally, the temperature was raised to a maximum of 260°C. at 0.3 mm Hg to remove volatile DOA, and 414 g of product was therebyobtained. The average polymerization degree of the product wascalculated to be 2.17, and its viscosity was 460 centipoise. With diolsof low volatility, a rapid reaction can be performed, but the fact thatthe reaction composition is inadequate deviates from the target.

EXAMPLE 24 di-2-ethylhexyl 1,2-propanediol adipate phthalate (Example ofManufacture of Hetero Complex Ester)

If the target compound is (2RPXAR+RPXAXAR+RPXAXPR), with 5 moles of P,A, 6 moles of X and 8(5+3) moles of R, and considering(2RAX+3RPXAR+RPXPR) as an intermediate, an excess of 2 moles of R can beused. If the corresponding amount 2R is removed in a transesterificationreaction, the target composition is obtained. An example of the reactionusing 1 mole of phthalic acid on a molar scale of 1/5, is shown below.

130 g of 2-ethylhexyl alcohol and 80 g toluene as solvent were added to148 g of phthalic anhydride, the atmosphere was replaced by nitrogen,and the reaction

1. A catalyst for an esterification reaction and/or atransesterification reaction, which is a gel-like substance comprising amixture of an alkoxytitanium, water-soluble polyol and water, or thereaction product thereof, wherein the number of moles of saidwater-soluble polyol and said water relative to 1 mole of titanium, isrespectively 1-50 moles and 1-60 moles.
 3. A method of producing anester comprising, a first step wherein a monofunctional alcohol and diolare simultaneously or separately added to a dibasic acid, a second stepwherein the reaction product of said acid and alcohol produced in thefirst step is separated to obtain an ester, and a third step wherein thereaction product separated in the second step is recycled to the firststep, 0.05-5 millimoles of the catalyst according to claim 1 relative toone mole of acid being used in said first step.
 4. A method of producingan ester comprising, a first step wherein a diol is reacted with anester produced beforehand from a dibasic acid and a monofunctionalalcohol, or an ester produced beforehand from a monofunctional alcoholand diol, a second step wherein unreacted ester is separated from theproduct produced in the first step to obtain another ester, and a thirdstep wherein unreacted ester separated in the second step is recycled tothe first step, 0.05-5 millimoles of the catalyst according to claim 1relative to one mole of acid being used in said first step.
 5. A methodof producing an ester comprising a step of reacting a reaction product,comprising an ester composition (RO(COACOOX)_(n)H) (n≧1) formed from thereaction of a dibasic acid (HOOCACOOH), diol (HOXOH) and terminalalcohol (ROH), in the presence of a catalyst according to claim 1 undera reduced pressure of 100 mm Hg or less, wherein in the formulae, A isan acid residue of the dibasic acid, X is the alcohol residue of thediol and R is the alcohol residue of the monofunctional alcohol.
 6. Amethod according to claim 5, wherein said reaction product furthercontains an ester compound represented by the general formula:R′O(COACOOXO)_(n)COACOOR′ wherein R′ are alkyl groups, which may beidentical or different and may be identical to R, A is an acid residueof a dibasic acid and X is the alcohol residue of a diol.
 7. A method ofproducing an ester comprising a step of a dehydration esterificationreaction and a following transesterification reaction of a dibasic acid,diol and monofunctional alcohol using the catalyst according to claim 1,wherein the required amounts of said monofunctional alcohol and saiddiol are distributed and continuously introduced into a reactor over thewhole period of the esterification reaction.
 10. A method according toclaim 7, wherein the molecular weight distribution of the esters is 2 orless.
 11. A method according to claim 3, wherein said alkoxytitanium istetrabutoxy titanium, tetraisopropyloxy titanium ortetraoctyloxytitanium, and said water-soluble polyol is ethylene glycol,propanediol, diethylene glycol or glycerine.
 12. A method according toclaim 4, wherein said alkoxytitanium is tetrabutoxy titanium,tetraisopropyloxy titanium or tetraoctyloxytitanium, and saidwater-soluble polyol is ethylene glycol, propanediol, diethylene glycolor glycerine.
 13. A method according to claim 5, wherein saidalkoxytitanium is tetrabutoxy titanium, tetraisopropyloxy titanium ortetraoctyloxytitanium, and said water-soluble polyol is ethylene glycol,propanediol, diethylene glycol or glycerine.